Quadrilateral has coordinates and . Draw the quadrilateral on the Cartesian plane. Rotate the image counterclockwise about the point . 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 ) | Rotated Image (Point ) |
---|---|---|---|
(0, 0) | (or ) | ||
(0, 0) | (or ) | ||
(0, 0) | (or ) |
Example A
Line drawn from (-4, 2) to (3, 2) has been rotated about the origin at an angle of CW. Draw the preimage and image and properly label each.
Solution:
Example B
The diamond is rotated CCW about the origin to form the image . 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 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 .
Concept Problem Revisited
Quadrilateral has coordinates and . Draw the quadrilateral on the Cartesian plane. Rotate the image counterclockwise about the point . Show the resulting image.
Vocabulary
- Center of rotation
- A center of rotation is the fixed point that a figure rotates about when undergoing a rotation.
- Rotation
- A rotation is a transformation that rotates (turns) an image a certain amount about a certain point.
- Image
- In a transformation, the final figure is called the image.
- Preimage
- In a transformation, the original figure is called the preimage.
- Transformation
- A transformation is an operation that is performed on a shape that moves or changes it in some way. There are four types of transformations: translations, reflections, dilations and rotations.
Guided Practice
1. Line drawn from (-3, 4) to (-3, 8) has been rotated CW about the point . Draw the preimage and image and properly label each.
2. The polygon below has been rotated CCW about the origin. Draw the rotated image and properly label each.
3. The purple pentagon is rotated about the point . Find the coordinates of the purple pentagon. On the diagram, draw and label the rotated pentagon.
Answers:
1.
Notice the direction of the angle is clockwise, therefore the angle measure is CW or .
2.
Notice the direction of the angle is counter-clockwise, therefore the angle measure is CCW or .
3.
The measure of . Therefore or . Notice the direction of the angle is counter-clockwise, therefore the angle measure is CCW or .
Practice
- Rotate the above figure clockwise about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure clockwise about the origin.
- Rotate the above figure about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure counterclockwise about the origin.
- Rotate the above figure about the origin.