Question

Triangle RST is rotated using the origin as the center of rotation. The preimage and image are shown in the graph below.

On a coordinate plane, triangle T R S has points (negative 2, negative 3), (2, negative 3), (0, negative 5). Triangle T prime R prime S prime has points (3.5, 0.8), (0.7, 3.8), (3.5, 3.8).

The figure is rotated counterclockwise. Which rotation could have taken place?
a 45° rotation
a 90° rotation
a 135° rotation
a 225° rotation

Answer 1

a 135° rotation.

Explanation:

As you can observe in the image attached, the preimage RST is a tringle "pointing" to the negaitve side of the vertical axis (taking point S as reference).

The transformed triangle R'S'T' is pointing to the diagonal of the first quadrant, with a 45°, approximately.

The rotation needed in such transformation would be 90° + 45° = 135°, becasue from -y to +x there're 90°, then we rotate 45° to reach the position of R'S'T'.

Therefore, the right asnwer is a 135° rotation.

Answer 2

a 135° rotation.

Explanation:

As you can observe in the image attached, the preimage RST is a tringle "pointing" to the negaitve side of the vertical axis (taking point S as reference).

The transformed triangle R'S'T' is pointing to the diagonal of the first quadrant, with a 45°, approximately.

The rotation needed in such transformation would be 90° + 45° = 135°, becasue from -y to +x there're 90°, then we rotate 45° to reach the position of R'S'T'.

Therefore, the right asnwer is a 135° rotation.