1. 1.2 Rotation Symmetry and Transformations
Math 9

2. What is rotation symmetry?
 When a shape can be turned about its centre of rotation so that it fits onto its outline more than once in a complete turn
 What is the point about which the rotation of an object or design turns called?
Centre of rotation
Notice this pinwheel has rotational symmetry but not line symmetry

3. What is the order of rotation
What is the order of rotation? The number of times a shape or design fits onto itself in one complete turn The angle of rotation is the smallest angle needed to turn a shape or design. It can be measured in… 1) Degrees or 2) Fraction of a turn

4. When we are working with the angle of rotation, it is important to remember that there are 360° around any given point. Describe how you would find the angle of rotation in both degree and fraction form.
Example: an equilateral triangle can rotate 3 times
Degree
360 ÷ 3 = 120
Divide 360 by number of turns
Fraction
1 𝟑
Make your numerator equal to one and you denominator is the number of turns.

5. Examples: No but it has line(ar) symmetry. Yes Centre of rotation
1. Decide whether each of the following figures has rotation symmetry. If so, identify the centre of rotation.
No but it has line(ar) symmetry.
Yes
Centre of rotation

6. 2. For each of the following figures, determine the order and the angle of rotation. Express the angles in both degrees and as fractions of a turn. 360 ÷ 4 = 90 360 ÷ 8 = 45 or or 𝟏 𝟒 𝟏 𝟖

7. 1.2 Symmetry Warm-up
Practice: p. 21 #4, 5, 7, 9, 14, 15, 17