Question

which of the following mapping is used for a 270 degree (counterclockwise) rotation? (1 point)
(x, y)→(y, -x)
(x, y)→(-y, x)
(x, y)→(-y, -x)
(x, y)→(-x, -y)

Explanation:

A 270-degree counterclockwise rotation around the origin has the standard mapping rule: (x, y) → (y, -x). This is derived from rotation matrix properties in coordinate geometry.

Answer:

A. (x, y) → (y, -x)