1. Rotations and Rotational Symmetry We are learning to…rotate a figure, describe a rotation, and identify rotational symmetries. Wednesday, December 02, 2015

2. 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.

3. + 90° 0°0° 90° 180° 270° 360° 45° + 45° 135° + 45° 225° 315° 22.5°

4. Estimating Rotations: Describe how the following figures have been rotated around the point of rotation. Original Object Point of Rotation Rotated Object Clockwis e: About 90° Counterclo ckwise: About 270° To find the missing rotation subtract from 360°(360 – 90 = ?)

5. Estimating Rotations: Describe how the following figures have been rotated around the point of rotation. Original Object Point of Rotation Rotated Object Clockwis e: About 315° Counterclo ckwise: About 45° To find the missing rotation subtract from 360°(360 – 45 = ?) 180° 90°

6. Estimating Rotations: Describe how the following figures have been rotated around the point of rotation. Original Object Point of Rotation Rotated Object Counterclo ckwise: About 225° Clockwise: About 135° To find the missing rotation subtract from 360°(360 – 135 =?) 180° 90°

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

8. 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 Symmetry 2. Divide 360 ° by the Order of the Rotational Symmetry 3. 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°.

9. Rotational Symmetry Practice Order of Rotational Symmetry: 1 2 3 4 5 6 6 Calculate the Rotational Symmetries 360 ÷ 6 =60° List all Rotational Symmetries: 60°, 120°, 180°, 240°, 300°, 360° (+60°) Practice finding Rotational Symmetries with your team!