Question

What is the mapping rule for a 180 degree rotation about the origin?

(x, y)g(–y, x)
(x, y)g(–y, –x)
(x, y)g(–x, –y)
(x, y)g(x, –y)

Answer 1

A 180° rotation about the origin maps every point to its opposite: (x, y) → (−x, −y). (So the correct choice is (x, y) g (−x, −y).)