Pearson Geometry Common Core, 2011
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Pearson Geometry Common Core, 2011 View details
Chapter Test
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Exercise 16 Page 607

The transformation (r_((90^(∘),O))∘ R_(y=1))(△XYZ) can be written as r_((90^(∘),O))(R_(y=1)(△XYZ)). This means that △XYZ will be reflected in the line y=1 and then the image will be rotated 90^(∘) about the origin O.

X''(2,3) Y''(-1,2) Z''(0,-2)

Practice makes perfect

The transformation (r_((90^(∘),O))∘ R_(y=1))(△XYZ) can be written as r_((90^(∘),O))(R_(y=1)(△XYZ)). This means that we will reflect △XYZ in the line y=1 and then rotate △XYZ 90^(∘) about the origin O. Let's begin by drawing the given figure.

We will do these transformations one at a time.

Reflection

Let's start by reflecting △XYZ using the line y=1 as the line of reflection. We will label this image △X'Y'Z'.

Rotation

Let's now rotate △X'Y'Z' 90^(∘) about the origin. Unless we are told otherwise, we perform rotations counterclockwise. We will label the new image △X''Y''Z''.


Final Image

Finally, we will show the preimage △XYZ and the image △X''Y''Z'' after the reflection and the rotation.

As we can see, X''(2,3), Y''(-1,2), and Z''(0,-2) are the coordinates of the image of △ XYZ.