Reflections, rotations and translations
3 exam-style questions. Answers and the mark for each step 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
Point A is . It is reflected in the line x = −1.
(a) Find the coordinates of the image B.
(b) Find the translation vector mapping A to B.
- Question 3
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 .
Answers and marks
Question 1
(a)
- B1 The vector written as a column.
(b)
- B1 The image .
(c)
- B1 The vector .
Question 2
(a)
- M1 The x-coordinates are equally far from the mirror line.
- A1 Correct answer:
(b)
- M1 Subtract original coordinates from image coordinates.
- A1 Correct answer:
Question 3
(a)
- P1 Finding the midpoint .
- P1 Using a gradient of 1, perpendicular to .
- A1 or any equivalent.
(b) Reflection in the line
- B1 Naming a reflection.
- B1 The mirror line .