Question

Triangle RST and its image, triangle R’S’T’, are graphed on the coordinate grid below.

On a coordinate plane, triangle R S T has points (0, 1), (negative 2, 2), (negative 1, 4). Triangle R prime S prime T prime has points (1, 0), (2, 2), (4, 1).
Which rotation, using the origin as the center of rotation, transformed RST to R’S’T’?
a 90° clockwise rotation
a 90° counterclockwise rotation
a 45° clockwise rotation
a 45° counterclockwise rotation

Answer 1

90° clockwise rotation.

Reason: A 90° clockwise rotation about the origin sends (x,y) → (y,−x). Applying this to the vertices:
- (0,1) → (1,0)
- (−2,2) → (2,2)
- (−1,4) → (4,1)

These are exactly R', S', T', so the transformation is 90° clockwise.