1. 4.3 Rotations

2. Coordinate Rules for Rotations
For a rotation about the origin (0,0), a rotation of the give angle measure CLOCKWISE will have the following rule 90 degrees: (x,y) → (y, - x) 180 degrees: (x,y) → (- x, - y) 270 degrees:(x, y) → (- y, x) **Remember 180 is just inverse, 90/270 are converse and change the sign of one coordinate.

3. Non 90 rotations
Lets rotate A(4, 1) B(4, 3) and c(7, 1) 150 degrees about point O, the origin, clockwise.
1) Draw a 150 degree angle with one side AO.
2) Place point A’ such that A’O = AO.
3) Repeat steps 1-2 for other vertices.

4. 4.3 Rotation Postulate
A rotation is a rigid motion.

5. Rotational Symmetry
A figure has rotational symmetry when it can be mapped onto itself by a rotation of 180 degrees or less about the center of the figure (center of symmetry).