Question

After a rotation of 90° about the origin, the coordinates of the vertices of the image of a triangle are A'(6,3), B'(-2, 1)

and C'(1,7). What are the coordinates of the vertices of the pre-image?
С.

Answer 1

• A(3, -6)
• B(1, 2)
• C(7, -1)

Explanation:

Rotation by -90° about the origin is the transformation ...

(x, y) ⇒ (y, -x)

So, your pre-image points are ...

A'(6, 3) ⇒ A(3, -6)

B'(-2, 1) ⇒ B(1, 2)

C'(1, 7) ⇒ C(7, -1)