3.4Rotations
Quick Answer
A rotation turns a figure about a center point. Coordinate rules about the origin: 90° CCW: (x,y)→(−y,x); 180°: (x,y)→(−x,−y); 270° CCW (= 90° CW): (x,y)→(y,−x). Every point stays the same distance from the center.
Essential Question
How do coordinate rules for rotations about the origin change the coordinates of each point?
Learning Goals
- 1Apply coordinate rules for 90°, 180°, and 270° rotations about the origin.
- 2Rotate figures about points other than the origin.
- 3Identify the angle and direction of rotation given a pre-image and image.
- 4Verify that a rotation is a rigid motion.
Key Vocabulary
Rotation
A transformation that turns a figure about a fixed point (center of rotation) by a given angle.
Center of rotation
The fixed point about which a figure is rotated.
Angle of rotation
The number of degrees a figure is rotated.
Counterclockwise (CCW)
The positive direction of rotation (standard convention).
Full lesson content coming soon
Worked examples, guided practice problems, a workbook, quiz, and downloadable PDF resources will be added to this lesson in Phase 2. The learning goals and vocabulary above reflect the complete lesson scope.