Rotations and Rotational SymmetryWe are learning to…rotate a figure, describe a rotation, and identify rotational symmetries.

Tuesday, April 18, 2023

Vocabulary A rotation turns a figure around a fixed

point a certain number of degrees either clockwise or counterclockwise. The new figure is congruent (exactly the same

shape and size) to the original figure.

+ 90°

+ 90°

+ 90°

+ 90°

0°

90°

180°

270°

360°

45°+ 45°

+ 45°

+ 45°

+ 45° 135°

+ 45°

+ 45°

+ 45°

+ 45°

225°

315°

22.5°

Estimating Rotations: Describe how the following figures have been

rotated around the point of rotation.

OriginalObject

Point of Rotation

RotatedObject

Clockwise:About 90°

Counterclockwise:About 270°

To find the missing rotation subtract from 360°(360 – 90 = ?)

Estimating Rotations: Describe how the following figures have been rotated

around the point of rotation.

OriginalObject

Point of Rotation

RotatedObject

Clockwise:About 315°

Counterclockwise:About 45°

To find the missing rotation subtract from 360°(360 – 45 = ?)

180°90°

Estimating Rotations: Describe how the following figures have been

rotated around the point of rotation.OriginalObject

Point of Rotation

RotatedObject

Counterclockwise:About 225°

Clockwise:About 135°

To find the missing rotation subtract from 360°(360 – 135 =?)

180°

90°

Vocabulary A figure has rotational symmetry when it can

be rotated less than 360° around a central point and then fit exactly on top of itself.

http://www.learner.org/courses/learningmath/geometry/session7/part_b/index.html

Rotational Symmetry Order of a Rotational Symmetry – The amount of

times that an object fits on top of itself when being rotated.

Calculating Rotational Symmetries:1. Find the Order of the Rotational Symmetry2. Divide 360 ° by the Order of the Rotational Symmetry3. This value represents the first Rotational Symmetry.4. Continue adding this value to find the next Rotational

Symmetry.5. Add this value until you reach 360°.

Rotational Symmetry PracticeOrder of Rotational Symmetry:

1

2

34

5

66

Calculate the Rotational Symmetries

360 ÷ 6 = 60°

List all Rotational Symmetries:

60°, 120°, 180°,

240°, 300°, 360°

(+60°) (+60°) (+60°)

(+60°) (+60°)

Practice finding Rotational Symmetries with your team!