Rotation of a point
Guided practice — solve each problem, check, then generate a fresh one.
Formula to apply
R(90°) (x, y) = (−y, x)
Problem
Rotate the point (4, 0) by 90° counter-clockwise about the origin. Give the image coordinates.
Working
- 1R(90°)(x, y) = (−y, x).
- 2x′ = −(0) = 0, y′ = 4 = 4.