### This lesson illustrates how to perform rotations in the coordinate plane around the origin for angles of 90 and 180 degrees using algebraic rules. Do you remember the Pearl Harbor movie and how the planes flew from one side of the screen to the other. The propellers of the plane motors kept rotating all the time. These rotations are accomplished using the coordinate plane and organizing the coordinates in a matrix to perform the necessary matrix operations to obtain one rotation at a time. Modern computers may perform this millions of times in a blink of an eye. These are the animations used in many of the movies you watch. Try to use the MARKER TOOLS menu to predict the landing position for the polygons to be rotated. Try to use the rotation algebraic rules. Then verify your rotation is in the same spot as the one of the example. Should that not be the case, then study the lesson previous slides to try to clarify the reason for they not overlaping.

** Lesson's Content **

** Lesson's Glossary **

**Rotation**

Transformation that maps the preimage onto the image along a center of rotation, by a given angle of rotation.

**Radii **

All the segments that connect the center of a circle, or arc with the circle or arc points.

**image **

Figure that has been transformated (mapped) through a translation, reflection, or rotation.

**pre-image **

Figure that is going to be mapped through a transformation (translation, reflection, or rotation.)

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