Riangle abc was transformed using the rule (x, y) → (–y, x). the vertices of the triangles are shown. a (–1, 1) b (1, 1) c (1, 4) a' (–1, –1) b' (–1, 1) c' (–4, 1) which best describes the transformation? the transformation was a 90° rotation about the origin. the transformation was a 180° rotation about the origin. the transformation was a 270° rotation about the origin. the transformation was a 360° rotation about the origin.