Coordinates and moving shapes · Usually met around P4
Rotations
Quarter turn clockwise: “right” becomes “down”.
How to do it
Method
Quarter turn clockwise: “right” becomes “down”
Clockwise 90° about A: 3 right of A → 3 below A
Another way
Tracing paper
Trace it, pin the centre, turn
In full
A rotation turns a shape about a point, the centre. Say three things: about which point, how far (90° is a quarter turn, 180° a half turn), and which way (clockwise, the way a clock's hands go, or anticlockwise). Turning about a corner, that corner stays put. A quarter turn swings each side from the centre round with it: clockwise, “right” becomes “down” and “up” becomes “right”; anticlockwise, “right” becomes “up”. A half turn: “right” becomes “left” and “up” becomes “down”, the same either way round. Or use tracing paper: trace the shape, hold the centre down with a pencil point and turn the paper.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Triangle ABC turns 90° clockwise about corner A. What is the x-coordinate of C′, C's new position?
Show the answer and working
Answer: 4
AC points 1 up; clockwise 90° turns “up” into “right”: C′ is 1 right of A, so x is 3 + 1 = 4.
Example 2
The blue triangle is the orange one turned 180° about A.
True or false?
Show the answer and working
Answer: False
After a half turn the side pointing right points left, and the side pointing up points down.
Example 3
The point (9, 5) turns 180° about (5, 4). Its new position is (□, □).
Fill in each box
Show the answer and working
Answer: 1，3
After a half turn the centre is exactly halfway between the point and its new place: x is 2 × 5 − 9 = 1, y is 2 × 4 − 5 = 3.
Practise it in the game →Coordinates and moving shapes · Free to start, unlimited questions, no download