Coordinate Plane: Rotations

[Pages:20]Coordinate Plane: Rotations

A rotation is a transformation that "turns" a figure about a point in either a clockwise or counterclockwise direction.

The point about which the figure rotates is called the center of rotation.

A rotation image is congruent to original figure and have different orientations.

To describe a rotation, tell whether the turn is clockwise or counterclockwise and the number of degrees the figure is turned around its center of rotation.

A 90? rotation is a quarter turn. A 180? rotation is a half turn. A 270? rotation is a three-quarter turn.

Rules for Counterclockwise Rotation About the Origin

90? rotation: (x,y)

(-y, x)

180? rotation: (x,y)

(-x, -y)

270? rotation: (x,y)

(y, -x)

Rules for Clockwise Rotation About the Origin

90? rotation: (x,y) 180? rotation: (x,y)

(y, -x) (-x, -y)

270? rotation: (x,y)

(-y, x)

You can draw a rotation of a point P(x,y) counterclockwise about the origin on a coordinate plane.

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