1. **Problem Statement:** Rotate the triangle with vertices at $ (3, -5) $, $ (4, 0) $, and $ (2, 1) $ by 90° counterclockwise about the origin. 2. **Formula for 90° Counterclockwise Rotation:** For any point $ (x, y) $, the coordinates after a 90° counterclockwise rotation about the origin are given by: $$ (x', y') = (-y, x) $$ 3. **Apply the formula to each vertex:** - For $ (3, -5) $: $$ (x', y') = (-(-5), 3) = (5, 3) $$ - For $ (4, 0) $: $$ (x', y') = (-(0), 4) = (0, 4) $$ - For $ (2, 1) $: $$ (x', y') = (-(1), 2) = (-1, 2) $$ 4. **Final rotated vertices:** $$ (5, 3), (0, 4), (-1, 2) $$ These are the coordinates of the triangle after a 90° counterclockwise rotation about the origin.