Question

1. A triangle is rotated 90° about the origin. What is true about the relationship between the image and the

pre-image?
(1 point)
The lengths of the sides and the measures of the angles are preserved, so the triangles are congruent.
The lengths of the sides are enlarged and measures of the angles are preserved, so the triangles are similar.
The lengths of the sides change and the measures of the angles change as well, so the triangles look nothing alike.
The lengths of the sides are reduced and measures of the angles are preserved, so one triangle is a reduction of the other.

Answer 1

the first answer option : all lengths and angles stay the same.

Explanation:

imagine you have a piece of plastic or glass of a triangular shape on your table.

now, lower your hand on the table, so that your thumb touches the table and one of your other fingers touches the triangle on the top.

and now twist your hand that your thumb stays at the same point, and your finger holding the triangle starts making a circular motion.

that finger is dragging the triangle along.

what happens to the triangle ? it keeps its original shape, and changes only its location and orientation.

that is what a rotation is.