Question

A triangle is rotated 90° about the origin. Which rule describes the transformation?

(x, y) → (–x, –y)
(x, y) → (–y, x)
(x, y) → (–y, –x)
(x, y) → (y, –x)

Answer 1

When a triangle (or any shape) is rotated 90° counterclockwise about the origin, the transformation rule that describes this is:

\((x, y) \rightarrow (-y, x)\)

So the correct answer is:

\((x, y) \rightarrow (-y, x)\)