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Graphs of Rotations

Graph rotated images given preimage and number of degrees

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Graphs of Rotations

Quadrilateral \begin{align*}WXYZ\end{align*} has coordinates \begin{align*}W(-5, -5), X(-2, 0), Y(2, 3)\end{align*} and \begin{align*}Z(-1, 3)\end{align*}. Draw the quadrilateral on the Cartesian plane. Rotate the image \begin{align*}110^\circ\end{align*} counterclockwise about the point \begin{align*}X\end{align*}. Show the resulting image.

Watch This

First watch this video to learn about graphs of rotations.

CK-12 Foundation Chapter10GraphsofRotationsA

Then watch this video to see some examples.

CK-12 Foundation Chapter10GraphsofRotationsB

Guidance

In geometry, a transformation is an operation that moves, flips, or changes a shape to create a new shape. A rotation is an example of a transformation where a figure is rotated about a specific point (called the center of rotation), a certain number of degrees.

For now, in order to graph a rotation in general you will use geometry software. This will allow you to rotate any figure any number of degrees about any point. There are a few common rotations that are good to know how to do without geometry software, shown in the table below.

Center of Rotation Angle of Rotation Preimage (Point \begin{align*}P\end{align*}) Rotated Image (Point \begin{align*}P^\prime\end{align*})
(0, 0) \begin{align*}90^\circ\end{align*}(or \begin{align*}-270^\circ\end{align*}) \begin{align*}(x, y)\end{align*} \begin{align*}(-y, x)\end{align*}
(0, 0) \begin{align*}180^\circ\end{align*}(or \begin{align*}-180^\circ\end{align*}) \begin{align*}(x, y)\end{align*} \begin{align*}(-x, -y)\end{align*}
(0, 0) \begin{align*}270^\circ\end{align*}(or \begin{align*}-90^\circ\end{align*}) \begin{align*}(x, y)\end{align*} \begin{align*}(y, -x)\end{align*}

Example A

Line \begin{align*}\overline{AB}\end{align*} drawn from (-4, 2) to (3, 2) has been rotated about the origin at an angle of \begin{align*}90^\circ\end{align*}CW. Draw the preimage and image and properly label each.

Solution:

Example B

The diamond \begin{align*}ABCD\end{align*} is rotated \begin{align*}145^\circ\end{align*}CCW about the origin to form the image \begin{align*}A^\prime B^\prime C^\prime D^\prime\end{align*}. On the diagram, draw and label the rotated image.

Solution:

Notice the direction is counter-clockwise.

Example C

The following figure is rotated about the origin \begin{align*}200^\circ\end{align*}CW to make a rotated image. On the diagram, draw and label the image.

Solution:

Notice the direction of the rotation is counter-clockwise, therefore the angle of rotation is \begin{align*}160^\circ\end{align*}.

Concept Problem Revisited

Quadrilateral \begin{align*}WXYZ\end{align*} has coordinates \begin{align*}W(-5, -5), X(-2, 0), Y(2, 3)\end{align*} and \begin{align*}Z(-1, 3)\end{align*}. Draw the quadrilateral on the Cartesian plane. Rotate the image \begin{align*}110^\circ\end{align*} counterclockwise about the point \begin{align*}X\end{align*}. Show the resulting image.

Guided Practice

1. Line \begin{align*}\overline{ST}\end{align*} drawn from (-3, 4) to (-3, 8) has been rotated \begin{align*}60^\circ\end{align*}CW about the point \begin{align*}S\end{align*}. Draw the preimage and image and properly label each.

2. The polygon below has been rotated \begin{align*}155^\circ\end{align*}CCW about the origin. Draw the rotated image and properly label each.

3. The purple pentagon is rotated about the point \begin{align*}A \ 225^\circ\end{align*}. Find the coordinates of the purple pentagon. On the diagram, draw and label the rotated pentagon.

1.

Notice the direction of the angle is clockwise, therefore the angle measure is \begin{align*}60^\circ\end{align*}CW or \begin{align*}-60^\circ\end{align*}.

2.

Notice the direction of the angle is counter-clockwise, therefore the angle measure is \begin{align*}155^\circ\end{align*}CCW or \begin{align*}155^\circ\end{align*}.

3.

The measure of \begin{align*}\angle BAB^\prime = m \angle BAE^\prime + m \angle E^\prime AB^\prime\end{align*}. Therefore \begin{align*}\angle BAB^\prime = 111.80^\circ + 113.20^\circ\end{align*} or \begin{align*}225^\circ\end{align*}. Notice the direction of the angle is counter-clockwise, therefore the angle measure is \begin{align*}225^\circ\end{align*}CCW or \begin{align*}225^\circ\end{align*}.

Explore More

1. Rotate the above figure \begin{align*}90^\circ\end{align*} clockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} clockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} counterclockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} counterclockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} clockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} clockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} counterclockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} counterclockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} clockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} clockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} counterclockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} counterclockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} clockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} clockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

1. Rotate the above figure \begin{align*}90^\circ\end{align*} counterclockwise about the origin.
2. Rotate the above figure \begin{align*}270^\circ\end{align*} counterclockwise about the origin.
3. Rotate the above figure \begin{align*}180^\circ\end{align*} about the origin.

To view the Explore More answers, open this PDF file and look for section 10.8.

Vocabulary Language: English

Rotation

Rotation

A rotation is a transformation that turns a figure on the coordinate plane a certain number of degrees about a given point without changing the shape or size of the figure.