Triangle rst was transformed using the rule (x, y) → (–x, –y). the vertices of the triangles are shown. r (1, 1) s (3, 1) t (1, 6) r' (–1, –1) s' (–3, –1) t' (–1, –6) 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.