Download presentation

Presentation is loading. Please wait.

Published byIris Mills Modified about 1 year ago

1
Honors Geometry Transformations Section 2 Rotations

2
A rotation is a transformation in which every point is rotated the same angle measure around a fixed point. The fixed point is called the center of rotation.

3
The ray drawn from the center of rotation to a point and the ray drawn from the center of rotation to the point’s image form an angle called the angle of rotation.

4

5
Rotations can be clockwise ( ) or counterclockwise ( ).

6
Let’s take a look at rotations in the coordinate plane.

7
Example 1: Rotate 180 clockwise about the origin (0, 0). Give the coordinates of _______ _______

8
Would the coordinates of and be different if we had rotated counterclockwise instead? NO

9
Rotations around the origin can be made very easily by simply rotating your paper the required angle measure. Note: The horizontal axis is always the x-axis and the vertical axis is always the y-axis.

10
Example 2: Rotate 90 clockwise about the origin. Give the coordinates of ________ ________

11
A B

12
Example 3: Rotate 90 counterclockwise about the origin. Give the coordinates of ________ ________ A B

13
For rotations of 90 0 around a point other than the origin, we must work with the slopes of the rays forming the angle of rotation. Remember: If two rays are perpendicular then their slopes are opposite reciprocals.

14
Example 4: Rotate 90 clockwise about the point (–1, 3).

15
Example 4: Rotate 90 counterclockwise about the point (–1, 3).

16
Example 6: Rotate 90 0 counterclockwise around the point (3, 0)

17
A figure has rotational symmetry if it can be rotated through an angle of less than 360 and match up with itself exactly.

18
Example 7: State the rotational symmetries of a square regular pentagon

19
Example 8: Name two capital letters that have 180 rotational symmetry.

Similar presentations

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google