Each transformation needs its full description. Reflection: the mirror line. Rotation: the angle, the direction and the centre. Translation: a column vector. Enlargement: the scale factor and the centre.
Name the transformation.
Give every detail it needs.
Check with tracing paper or by moving one vertex at a time.
Watch out A rotation without its centre, or a translation without its vector, loses marks.
See it worked
Worked exampleNon-calculator·3 marks
This question is about translations.
(a) The point A(2,5) is translated to the point A′(6,1). Write down the column vector of the translation.
(b) The point B(−3,2) is translated by the vector (−25). Write down the coordinates of the image of B.
(c) Write down the column vector that translates A′ back to A.
(a) Across: 6−2=4. Up: 1−5=−4 (down 4).
(b) (−3+(−2),2+5)=(−5,7).
(c) Going back reverses the movement, so both components change sign.
Answer (a) (4−4); (b) (−5,7); (c) (−44)
Your turn
Question 1Non-calculator·3 marks
Point P has coordinates (−3, 5). It is translated by the column vector (7, −9), meaning 7 units right and 9 units down. Write the coordinates of its image.
Question 2Non-calculator·4 marks
Point A is (3,−2). Rotate A 90 degrees anticlockwise about the origin.
(a) Find the image coordinates.
(b) Find the image after another 90 degree anticlockwise turn.
Question 3Non-calculator·4 marks
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).
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