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7I-Rotation and Reflection

Question 3:

A(3,3),C(0,0)

We’ll apply standard rotation rules about the origin.

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Rotation

Formula

Direction

90° clockwise

((x, y) → (y, -x))

right turn

90° anticlockwise

((x, y) → (-y, x))

left turn

180° (clockwise or anticlockwise)

((x, y) → (-x, -y))

half turn

270° clockwise (= 90° anticlockwise)

((x, y) → (-y, x))

same as 90° anticlockwise

360°

((x, y) → (x, y))

full circle, same point

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Final Answer

Rotation

A′ Coordinates

a) 180° clockwise

(–3, –3)

b) 90° clockwise

(3, –3)

c) 90° anticlockwise

(–3, 3)

d) 270° clockwise

(–3, 3)

e) 360° anticlockwise

(3, 3)

f) 180° anticlockwise

(–3, –3)

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Question 4

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Rotation

Formula

Description

90° anticlockwise

(x, y) → (–y, x)

turn left

180°

(x, y) → (–x, –y)

half turn

90° clockwise

(x, y) → (y, –x)

turn right

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Rotation

A′

B′

D′

90° anticlockwise

(0, –1)

(2, 0)

(0, –3)

180°

(1, 0)

(0, 2)

(3, 0)

90° clockwise

(0, 1)

(–2, 0)

(0, 3)

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