Question

Which shows the image of ΔRST after the rotation (x, y) → (y, –x)?

On a coordinate plane, a triangle has points R (negative 2, 1), S (1, 3), T (negative 1, 8).

On a coordinate plane, a triangle has points R prime (1, 2), S prime (3, negative 1), T prime (7, 1).
On a coordinate plane, a triangle has points R prime (1, negative 2), S prime (3, 1), T prime (7, negative 1).

Answer 1

Apply (x,y) → (y, −x) to each vertex:

- R(−2,1) → R' = (1, −(−2)) = (1,2)
- S(1,3) → S' = (3, −1)
- T(−1,8) → T' = (8, 1)

So the image is R'(1,2), S'(3,−1), T'(8,1). Neither of the two answer sets you listed matches that exactly. (If T were (−1,7) instead of (−1,8), the first listed set would be correct.)