Reflections, rotations and translations
8 exam-style questions, grades 2 to 6. Worked solutions and the marks are on the last page.
- Question 1
This question is about translations.
(a) The point is translated to the point . Write down the column vector of the translation.
(b) The point is translated by the vector . Write down the coordinates of the image of .
(c) Write down the column vector that translates back to .
- Question 2
(a) Point P has coordinates (, 5). It is translated by the column vector (7, ), meaning 7 units right and 9 units down. Write the coordinates of its image.
- Question 3
(a) Point Q has coordinates (, 2). Reflect Q in the y-axis. Write the coordinates of its image.
- Question 4
Triangle has vertices , and .
(a) Triangle is rotated clockwise about the origin. Write down the coordinates of the image of the vertex .
(b) Triangle has vertices , and . Describe fully the single transformation that maps triangle onto triangle .
- Question 5
Point A is . Rotate A 90 degrees anticlockwise about the origin.
(a) Find the image coordinates.
(b) Find the image after another 90 degree anticlockwise turn.
- Question 6
A translation sends A to B.
(a) Find the translation vector.
(b) Find the image of C.
- Question 7
Triangle T has vertices (1, 2), (4, 2) and (1, 4).
(a) T is reflected in the line y = x. Write down the image of the vertex (4, 2).
(b) T is rotated 180° about the origin. Write down the image of the vertex (1, 4).
(c) T is translated so that (1, 2) moves to (6, −1). Write the translation vector as (x, y).
- Question 8
This question is about reflections.
(a) The point is reflected in the line . Its image is . Find an equation of the line .
(b) Triangle has vertices , and . Triangle has vertices , and . Describe fully the single transformation that maps onto .
Worked solutions and marks
Question 1
(a)
- Across: . Up: (down 4).
- B1 The vector written as a column.
(b)
- .
- B1 The image .
(c)
- Going back reverses the movement, so both components change sign.
- B1 The vector .
Question 2
(a)
- Add the horizontal component: + 7 = 4.
- Add the vertical component: 5 9 = , giving (4, ).
- P1 Establishing or an equivalent valid method.
- P1 Establishing or an equivalent valid method.
- A1 Correct answer:
Question 3
(a)
- Reflection in the y-axis changes the sign of x and leaves y unchanged.
- The image is (6, 2).
- P1 Establishing or an equivalent valid method.
- A1 Correct answer:
Question 4
(a)
- A clockwise turn about sends to .
- So . Check: the point moves from the first quadrant to the fourth.
- B1 The image .
(b) Rotation of about the origin
- Each vertex goes to .
- That is a half turn: rotation about . A half turn needs no direction.
- B1 Naming a rotation.
- B1 Both (a half turn) and the centre .
Question 5
(a)
- A quarter turn anticlockwise sends (x,y) to (-y,x).
- Therefore .
- M1 A quarter turn anticlockwise sends (x,y) to (-y,x).
- A1 Correct answer:
(b)
- Apply the same rotation rule a second time.
- Therefore .
- M1 Apply the same rotation rule a second time.
- A1 Correct answer:
Question 6
(a)
- Subtract the starting coordinates from the final coordinates.
- Therefore .
- M1 Subtract the starting coordinates from the final coordinates.
- A1 Correct answer:
(b)
- Apply the same displacement to C.
- Therefore .
- M1 Apply the same displacement to C.
- A1 Correct answer:
Question 7
(a)
- Therefore .
- B1 Correct answer:
(b)
- Therefore .
- B1 Correct answer:
(c)
- Subtract the original coordinates from the image coordinates.
- Therefore .
- M1 Subtract the original coordinates from the image coordinates.
- A1 Correct answer:
Question 8
(a)
- The mirror line passes through the midpoint of : .
- The gradient of is . The mirror line is perpendicular to , so its gradient is .
- Through with gradient 1:
- P1 Finding the midpoint .
- P1 Using a gradient of 1, perpendicular to .
- A1 or any equivalent.
(b) Reflection in the line
- Each vertex goes to , for example .
- That is a reflection in the line .
- B1 Naming a reflection.
- B1 The mirror line .