High School Math based on the topics required for the Regents Exam conducted by NYSED.

When working in the coordinate plane, assume the center of rotation to be the origin unless told otherwise.

A positive angle of rotation turns the figure counterclockwise, and a negative angle of rotation turns the figure in a clockwise direction.

Rotation of 90 degrees |
R(x,y) = (–y, x) |

Rotation of 180 degrees |
R(x,y) = (–x, –y) |

Rotation of 270 degrees |
R(x,y) = (y , –x) |

Rotate 90 degrees

Rotating a polygon around the origin.

For a 90 degree rotation around the origin, switch the x,y values of each ordered pair for the location of the new point.

Rotate 90 degrees counter-clockwise.

Draw an image of a polygon with vertices A(2,2), B(4,3), C(4,5) and D(1,4). Graph the image of quadrilateral ABCD after a rotation 90° counterclockwise about the origin and write the coordinates of the vertices.

Step 1: Find the points of the vertices.

Step 2: Switch the x and y values for each point.

Step 3: Multiply the new x-values by -1.

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