Question

Triangle GHJ and its image, triangle G’H’J’, are graphed on the coordinate grid below.

On a coordinate plane, triangle G H J has points (2, 5), (3, 3), (1, 4). Triangle G prime H prime J prime has points (negative 5, 2), (negative 3, 3), (negative 4, 1).

Which rotation, using the origin as the center of rotation, occurred?
a 90° clockwise rotation
a 90° counterclockwise rotation
a 45° clockwise rotation
a 45° counterclockwise rotation

Answer 1

A 90° counterclockwise rotation.

Reason: A 90° CCW rotation about the origin sends (x,y) → (−y,x). Applying this:
- (2,5) → (−5,2)
- (3,3) → (−3,3)
- (1,4) → (−4,1)

which matches G′, H′, J′.