Year 4: Completing symmetrical figures
Part of the Year 4 shapes, angles and symmetry chapter. Chapter overview · whole chapter on one page · Download worksheet (PDF) · Answers (PDF)
Completing symmetrical figures
A symmetrical figure looks the same on both sides of its mirror line. If you are given one half and the mirror line, you can complete the figure by drawing the other half. Each point in the new half is the same distance from the mirror line as the matching point in the first half, but on the other side.
- Find the mirror line.
- Take one shaded square (or one corner). Count how far it is from the mirror line.
- Go the same distance on the other side and shade the matching square.
- Do every square. Check that both sides match.
Different mirror lines. The mirror line can be vertical (up and down), horizontal (across) or diagonal (corner to corner). For a diagonal line, a square swaps its row and column with its partner: the square in column D, row 2 goes to column B, row 4.
Key ideas
- A symmetrical figure matches on both sides of the mirror line.
- Each point and its partner are the same distance from the mirror line, on opposite sides.
- Count squares (or dots) from the mirror line, not from the edge of the grid.
- For a diagonal mirror line, the row and the column swap.
- Check by folding: the two sides must match exactly.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a vertical line (up and down).
- Find the partner of each shaded square. Count the squares between each shaded square and the mirror line. The partner has the same number of squares between it and the mirror line, on the other side.A4 has 3 squares between it and the mirror line, so its partner has 3 squares between it and the mirror line on the other side: H4.
B3 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G3.
B4 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G4.
C2 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F2.
C3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F3.
C4 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F4.
D1 touches the mirror line, so E1 touches it on the other side.
D2 touches the mirror line, so E2 touches it on the other side.
D3 touches the mirror line, so E3 touches it on the other side.
D4 touches the mirror line, so E4 touches it on the other side.
D5 touches the mirror line, so E5 touches it on the other side.
D6 touches the mirror line, so E6 touches it on the other side. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 12 more squares: E1, E2, E3, E4, E5, E6, F2, F3, F4, G3, G4, H4.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a horizontal line (across).
- Find the partner of each shaded square. Each square goes the same distance from the mirror line, on the other side (up and down).A4 touches the mirror line, so A5 touches it on the other side.
B3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: B6.
B4 touches the mirror line, so B5 touches it on the other side.
C2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: C7.
C3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: C6.
C4 touches the mirror line, so C5 touches it on the other side.
D2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: D7.
D3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: D6.
D4 touches the mirror line, so D5 touches it on the other side.
E3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: E6.
E4 touches the mirror line, so E5 touches it on the other side.
F4 touches the mirror line, so F5 touches it on the other side. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 12 more squares: A5, B5, B6, C5, C6, C7, D5, D6, D7, E5, E6, F5.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a diagonal line (from the top left corner to the bottom right corner).
- Find the partner of each shaded square. With a diagonal mirror line, a square in column C and row R goes to column R and row C. The row and column swap.A1 is on the mirror line, so it stays where it is.
A2: swap the column and row, so its partner is B1.
B2 is on the mirror line, so it stays where it is.
B3: swap the column and row, so its partner is C2.
B4: swap the column and row, so its partner is D2.
C4: swap the column and row, so its partner is D3.
C5: swap the column and row, so its partner is E3.
C6: swap the column and row, so its partner is F3.
D6: swap the column and row, so its partner is F4. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 7 more squares: B1, C2, D2, D3, E3, F3, F4.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each corner (vertex) of the shape in the mirror line. Corners on the mirror line stay where they are. Then join the new corners to make the other half of the shape.
- Find the mirror line. The red dashed line is the mirror line. Some corners of the shape are on it.The mirror line is a vertical line (up and down).
- Find the partner of each corner that is not on the line. Each partner is the same distance from the mirror line, on the other side.Corner A is 3 dots to the right of the mirror line and 0 dots up. Its partner is 3 dots to the left of the line, 0 up.
Corner B is 3 dots to the right of the mirror line and 3 dots up. Its partner is 3 dots to the left of the line, 3 up.
Corner C is 2 dots to the right of the mirror line and 5 dots up. Its partner is 2 dots to the left of the line, 5 up. - Join the corners. Join the new corners in order to finish the shape. Orange is the half you were given and green is the new half.
Check. Fold along the mirror line: the two halves match exactly. The completed shape is a hexagon. ✓
Watch out. Take care to count the dots from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each corner (vertex) of the shape in the mirror line. Corners on the mirror line stay where they are. Then join the new corners to make the other half of the shape.
- Find the mirror line. The red dashed line is the mirror line. Some corners of the shape are on it.The mirror line is a diagonal line (from the top left corner to the bottom right corner).
- Find the partner of each corner that is not on the line. With a diagonal mirror line, the numbers across and up swap.Corner A is 4 across and 1 up. Swap the numbers: its partner is 1 across and 4 up.
Corner B is 5 across and 3 up. Swap the numbers: its partner is 3 across and 5 up. - Join the corners. Join the new corners in order to finish the shape. Orange is the half you were given and green is the new half.
Check. Fold along the mirror line: the two halves match exactly. The completed shape is a hexagon. ✓
Watch out. Take care to count the dots from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Check each shaded square against its partner. Find the square in the wrong place.
- Look at the attempt. Orange squares are shaded. The mirror line is vertical.
- Reflect the original squares. Work out where every partner should be.The new squares should be: E1, E2, E3, E4, E5, E6, F2, F3, F4, G3, G4, H4.
- Compare. Find a shaded square that should not be there, and a square that is missing.is shaded but should not be. F2 is missing.
- Show the corrected figure. The wrong square is red. The correct square is green.
Check. Every square on the right is now the mirror image of a square on the left. ✓
Watch out. Check the figure square by square.
Watch out
Count from the mirror line, not from the edge. A square that is 2 squares from the mirror line has a partner that is 2 squares from the mirror line on the other side. Also, do not slide the shape across: a reflection is a flip, so the shape faces the other way.Exercise 9H Complete the symmetrical figure
Non-calculatorKey words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a vertical line (up and down).
- Find the partner of each shaded square. Count the squares between each shaded square and the mirror line. The partner has the same number of squares between it and the mirror line, on the other side.A4 has 3 squares between it and the mirror line, so its partner has 3 squares between it and the mirror line on the other side: H4.
B3 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G3.
B4 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G4.
C2 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F2.
C3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F3.
C4 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F4.
D1 touches the mirror line, so E1 touches it on the other side.
D2 touches the mirror line, so E2 touches it on the other side.
D3 touches the mirror line, so E3 touches it on the other side.
D4 touches the mirror line, so E4 touches it on the other side.
D5 touches the mirror line, so E5 touches it on the other side.
D6 touches the mirror line, so E6 touches it on the other side. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 12 more squares: E1, E2, E3, E4, E5, E6, F2, F3, F4, G3, G4, H4.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a vertical line (up and down).
- Find the partner of each shaded square. Count the squares between each shaded square and the mirror line. The partner has the same number of squares between it and the mirror line, on the other side.A1 has 3 squares between it and the mirror line, so its partner has 3 squares between it and the mirror line on the other side: H1.
A2 has 3 squares between it and the mirror line, so its partner has 3 squares between it and the mirror line on the other side: H2.
B2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G2.
B3 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G3.
B4 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: G4.
C3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F3.
C4 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F4.
C5 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: F5.
D4 touches the mirror line, so E4 touches it on the other side. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 9 more squares: E4, F3, F4, F5, G2, G3, G4, H1, H2.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a horizontal line (across).
- Find the partner of each shaded square. Each square goes the same distance from the mirror line, on the other side (up and down).A4 touches the mirror line, so A5 touches it on the other side.
B3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: B6.
B4 touches the mirror line, so B5 touches it on the other side.
C2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: C7.
C3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: C6.
C4 touches the mirror line, so C5 touches it on the other side.
D2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: D7.
D3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: D6.
D4 touches the mirror line, so D5 touches it on the other side.
E3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: E6.
E4 touches the mirror line, so E5 touches it on the other side.
F4 touches the mirror line, so F5 touches it on the other side. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 12 more squares: A5, B5, B6, C5, C6, C7, D5, D6, D7, E5, E6, F5.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a horizontal line (across).
- Find the partner of each shaded square. Each square goes the same distance from the mirror line, on the other side (up and down).A1 has 3 squares between it and the mirror line, so its partner has 3 squares between it and the mirror line on the other side: A8.
B2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: B7.
C3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: C6.
C4 touches the mirror line, so C5 touches it on the other side.
D3 has 1 square between it and the mirror line, so its partner has 1 square between it and the mirror line on the other side: D6.
D4 touches the mirror line, so D5 touches it on the other side.
E2 has 2 squares between it and the mirror line, so its partner has 2 squares between it and the mirror line on the other side: E7.
F1 has 3 squares between it and the mirror line, so its partner has 3 squares between it and the mirror line on the other side: F8. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 8 more squares: A8, B7, C5, C6, D5, D6, E7, F8.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a diagonal line (from the top left corner to the bottom right corner).
- Find the partner of each shaded square. With a diagonal mirror line, a square in column C and row R goes to column R and row C. The row and column swap.A5: swap the column and row, so its partner is E1.
B5: swap the column and row, so its partner is E2.
B6: swap the column and row, so its partner is F2.
C3 is on the mirror line, so it stays where it is.
C4: swap the column and row, so its partner is D3.
D4 is on the mirror line, so it stays where it is.
D5: swap the column and row, so its partner is E4.
F6 is on the mirror line, so it stays where it is. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 5 more squares: D3, E1, E2, E4, F2.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each shaded square in the mirror line. Each square and its partner are the same distance from the mirror line, on opposite sides.
- Find the mirror line. The red dashed line is the mirror line.The mirror line is a diagonal line (from the top left corner to the bottom right corner).
- Find the partner of each shaded square. With a diagonal mirror line, a square in column C and row R goes to column R and row C. The row and column swap.A1 is on the mirror line, so it stays where it is.
A2: swap the column and row, so its partner is B1.
A3: swap the column and row, so its partner is C1.
B3: swap the column and row, so its partner is C2.
B4: swap the column and row, so its partner is D2.
B5: swap the column and row, so its partner is E2.
C5: swap the column and row, so its partner is E3.
D6: swap the column and row, so its partner is F4. - Shade the new squares. Orange squares were given. Green squares are the new ones.Shade 7 more squares: B1, C1, C2, D2, E2, E3, F4.
Check. Fold along the mirror line: every green square lands on an orange square. ✓
Watch out. Count the squares from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each corner (vertex) of the shape in the mirror line. Corners on the mirror line stay where they are. Then join the new corners to make the other half of the shape.
- Find the mirror line. The red dashed line is the mirror line. Some corners of the shape are on it.The mirror line is a vertical line (up and down).
- Find the partner of each corner that is not on the line. Each partner is the same distance from the mirror line, on the other side.Corner A is 2 dots to the right of the mirror line and 1 dot up. Its partner is 2 dots to the left of the line, 1 up.
Corner B is 3 dots to the right of the mirror line and 3 dots up. Its partner is 3 dots to the left of the line, 3 up.
Corner C is 1 dot to the right of the mirror line and 3 dots up. Its partner is 1 dot to the left of the line, 3 up.
Corner D is 1 dot to the right of the mirror line and 5 dots up. Its partner is 1 dot to the left of the line, 5 up. - Join the corners. Join the new corners in order to finish the shape. Orange is the half you were given and green is the new half.
Check. Fold along the mirror line: the two halves match exactly. The completed shape is an octagon. ✓
Watch out. Take care to count the dots from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each corner (vertex) of the shape in the mirror line. Corners on the mirror line stay where they are. Then join the new corners to make the other half of the shape.
- Find the mirror line. The red dashed line is the mirror line. Some corners of the shape are on it.The mirror line is a horizontal line (across).
- Find the partner of each corner that is not on the line. Each partner is the same distance from the mirror line, on the other side.Corner A is 2 dots above the mirror line and 0 dots across. Its partner is 2 dots below the line, 0 across.
Corner B is 3 dots above the mirror line and 3 dots across. Its partner is 3 dots below the line, 3 across.
Corner C is 2 dots above the mirror line and 6 dots across. Its partner is 2 dots below the line, 6 across. - Join the corners. Join the new corners in order to finish the shape. Orange is the half you were given and green is the new half.
Check. Fold along the mirror line: the two halves match exactly. The completed shape is a hexagon. ✓
Watch out. Take care to count the dots from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect each corner (vertex) of the shape in the mirror line. Corners on the mirror line stay where they are. Then join the new corners to make the other half of the shape.
- Find the mirror line. The red dashed line is the mirror line. Some corners of the shape are on it.The mirror line is a diagonal line (from the top left corner to the bottom right corner).
- Find the partner of each corner that is not on the line. With a diagonal mirror line, the numbers across and up swap.Corner A is 4 across and 1 up. Swap the numbers: its partner is 1 across and 4 up.
Corner B is 5 across and 3 up. Swap the numbers: its partner is 3 across and 5 up. - Join the corners. Join the new corners in order to finish the shape. Orange is the half you were given and green is the new half.
Check. Fold along the mirror line: the two halves match exactly. The completed shape is a hexagon. ✓
Watch out. Take care to count the dots from the mirror line, not from the edge of the grid.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. A vertical mirror line has no squares on it, so every shaded square has its own partner. The finished figure has twice as many shaded squares as the half you started with.
- Count the shaded squares you are given. Count carefully, row by row.There are 10 shaded squares.
- Find the number of new squares. Each square has one partner.10 new squares
- Add. Given squares plus new squares.10 + 10 = 20
Check. 2 × 10 = 20. ✓
Watch out. Count the whole finished figure, not only the new squares.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Reflect the shaded squares in the mirror line. A reflection is a flip, so the shape must face the other way. Then compare with each picture.
- Reflect the original squares. Each square goes the same distance from the mirror line on the other side.
- Check each picture. B is a flip. A is the shape slid across (not flipped). C is turned upside down.A: the shape is slid across, not flipped.
B: matches the reflection.
C: this is the shape turned upside down. - Choose. The correct picture is B.
Check. In picture B the two sides are mirror images. ✓
Watch out. A slide is not a reflection.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Check each shaded square against its partner. Find the square in the wrong place.
- Look at the attempt. Orange squares are shaded. The mirror line is vertical.
- Reflect the original squares. Work out where every partner should be.The new squares should be: E1, E2, E3, E4, E5, E6, F2, F3, F4, G3, G4, H4.
- Compare. Find a shaded square that should not be there, and a square that is missing.is shaded but should not be. F2 is missing.
- Show the corrected figure. The wrong square is red. The correct square is green.
Check. Every square on the right is now the mirror image of a square on the left. ✓
Watch out. Check the figure square by square.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Compare the squares on both sides of the mirror line. Find the squares on the left that do not have a partner on the right.
- Look at the figure. Some squares on the right are missing.
- Reflect every shaded square on the left. Check that its partner on the right is shaded.The partners that are not shaded are E1, E2, F2.
- Show the finished figure. The green squares are the ones to shade.
Check. Now every square has a partner. ✓
Watch out. Check the squares on the right too, in case a square there has no partner.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. There are two mirror lines. First reflect the shaded squares in the vertical line. Then reflect everything in the horizontal line.
- Reflect in the vertical mirror line. The vertical line is on the left of D. Each square goes to the other side of it.
- Reflect all the squares in the horizontal mirror line. The shaded squares at the top now go to the bottom.
- Count the shaded squares. Original squares, then the squares from each reflection.5 + 5 = 10, and 10 + 10 = 20
Check. 4 × 5 = 20. The finished pattern has 4 copies of the first group of squares. ✓
Watch out. Do the first reflection completely before you start the second one.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. Squares on the diagonal mirror line are their own partners, so they are not doubled. Squares off the line each get a new partner.
- Count the shaded squares on the mirror line. These stay where they are.A1, B2, D4: 3 squares.
- Count the shaded squares off the line. Each one gets a new partner.6 − 3 = 3 squares, so 3 new squares.
- Add everything. Original squares + new squares.6 + 3 = 9
Check. 2 × 3 + 3 = 9. ✓
Watch out. Not every square gets doubled with a diagonal mirror line.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. With a diagonal mirror line (top left to bottom right), the column and row swap. Work out the partner and compare with the claim.
- Write the position of D2. Column letter and row number.D2: column D (number 4), row 2.
- Swap the column and the row. The column number becomes the row, and the row becomes the column.column B (number 2), row 4 = B4
- Compare. Priya says B4.Priya is right. The partner is B4.
Check. The partner of B4 is D2, which swaps back. ✓
Watch out. The column letter becomes the row number.
Key words. A mirror line is the line a shape is reflected in. Each point of the reflection is the same distance from the mirror line as the point it matches, but on the other side.
Method. With a diagonal mirror line (top left to bottom right), the column and row swap. Work out the partner and compare with the claim.
- Write the position of C4. Column letter and row number.C4: column C (number 3), row 4.
- Swap the column and the row. The column number becomes the row, and the row becomes the column.column D (number 4), row 3 = D3
- Compare. Noah says C3.Noah is wrong. The partner is D3.
Check. The partner of D3 is C4, which swaps back. ✓
Watch out. The column letter becomes the row number.