Rotation of 90 Degrees Counterclockwise

Rotation of 90 Degrees Counterclockwise

How to solve the rotation of 90 degrees counterclockwise problems: formula, example, and its solution.

Formula

The image of a point (x, y), whose image is under a rotation of 90 degrees counterclockwise about the origin, is (-y, x).

The image of a point (x, y),
whose image is under a rotation of 90 degrees
counterclockwise about the origin,
is (-y, x).

Example

Triangle ABC has vertices A(1, 2), B(5, 4), and C(3, 1). Its image is under a rotation of 90 degrees counterclockwise about the origin. Find the coordinates of the vertices of the image.

Rotation of 90º counterclockwise:
(x, y) → (-y, x)