Glencoe Math: Course 3, Volume 2
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Glencoe Math: Course 3, Volume 2 View details
3. Rotations
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Exercise 1 Page 478

Start by rotating a point using a protractor to measure the angle.

Graph:

Coordinates: X'(3,- 1), Y'(0,-3), Z'(-1,1)

Practice makes perfect

Let's start by plotting the given vertices X(3,- 1), Y(5,- 4), and Z(1,- 5). Then we will connect them with line segments to draw the triangle.

quadrilateral

We want to rotate the image of △ XYZ by 270^(∘) counterclockwise about vertex X. A rotation by 270^(∘) counterclockwise ends up in the same place as a rotation by 90^(∘) clockwise. For simplicity, let's start by rotating only one point. We will use vertex Z. We can use a protractor to draw a ray that makes a 90^(∘) angle with XZ at X.

On this ray, we will mark a point Z' such that XZ' is the same length as XZ. This is the image of Z after the rotation.

Next, to obtain Y' we will repeat the same process. Furthermore, since X is the point at which the triangle is rotated, X' will be in the same position as X. The coordinates of the images of the vertices are X'(3,-1), Y'(0,-3), and Z'(- 1,1).

images

Finally, we will connect X', Y', and Z' to obtain the image of XYZ.

image

Extra

Visualizing the Rotation
Let's rotate XYZ 270^(∘) counterclockwise about X so that we can see how it is mapped onto X'Y'Z'.

rotate