Question

Triangle is reflected across the y-axis and then dilated by a factor of centered at the origin. Which statement correctly describes the resulting image, triangle ?

Image of right triangle ABC in a graph with vertices A (minus 4, minus 2), B (4, minus 2), and C (4, 4)
A.
The reflection preserves the side lengths and angles of triangle . The dilation preserves angles but not side lengths.
B.
Both the reflection and dilation preserve the side lengths and angles of triangle .
C.
Neither the reflection nor the dilation preserves the side lengths and angles of triangle .
D.
The dilation preserves the side lengths and angles of triangle . The reflection does not preserve side lengths and angles.

Answer 1

A. The reflection preserves the side lengths and angles of triangle . The dilation preserves angles but not side lengths.

Explanation:

Reflection is a rigid transformation. It preserves both angles and side lengths. Dilation preserves angles, but changes all lengths by the same scale factor.

Application

The described triangle was subject to reflection, which preserves angles and lengths. It was also subject to dilation, which preserves angles, but not lengths.

The appropriate description is that of choice A.