Question

Using the Rotation Rule for 90° Rotations
M (3, –6) is rotated 90° counterclockwise.

(x, y) → (–y, x)

1. Switch the x- and y-coordinates:
(6, –3)

2. Multiply the new x-coordinate by –1:
(6(–1), –3)

3. Simplify:
(–6, –3)

Mary Beth used the mapping rule to find the coordinates of a point that had been rotated 90° counterclockwise around the origin.

Examine the steps to determine whether she made an error.

The student made
.

Answer 1

The student made an error in Step 1. Swapping (3, −6) gives (−6, 3), not (6, −3). Applying (x,y) → (−y,x) correctly yields (6, 3).