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Rotations and Rotational Symmetry

Rotations and Rotational Symmetry. We are learning to…rotate a figure, describe a rotation, and identify rotational symmetries. Wednesday, April 2, 2014. Vocabulary. A rotation turns a figure around a fixed point a certain number of degrees either clockwise or counterclockwise .

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Rotations and Rotational Symmetry

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  1. Rotations and Rotational Symmetry We are learning to…rotate a figure, describe a rotation, and identify rotational symmetries. Wednesday, April 2, 2014

  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. Degrees in a Circle Review 360° 0° 22.5° 315° 45° + 45° + 45° + 90° + 90° + 45° + 45° 270° 90° + 45° + 45° + 90° + 90° + 45° + 45° 135° 225° 180°

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

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

  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

  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: • Find the Order of the Rotational Symmetry • Divide 360 ° by the Order of the Rotational Symmetry • This value represents the first Rotational Symmetry. • Continue adding this value to find the next Rotational Symmetry. • Add this value until you reach 360°.

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

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