Question

Triangle RST was transformed using the rule (x, y) → (–x, –y). The vertices of the triangles are shown.

R (1, 1) R' (–1, –1)
S (3, 1) S' (–3, –1)
T (1, 6) 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.

Answer 1

option (B on edgen

Answer 2

The transformation using the rule (x, y) → (–x, –y) is a refrection across the line y = x about the origin.

Clearly from the coordinates given, it can be seen that the original triangle is in the first quadrant and the image is in the third quadrant.

Therefore, the transformation was a 180° rotation about the origin.