Middle School Resource

Alternate Exterior Angles by Math Open Reference

This interactive web-based resource demonstrates the alternate exterior angles that are formed where a transversal crosses two lines. The interactive application shows the two possible pairs of angles alternating when in animation mode. By dragging the three lines, it can be seen that the angles are congruent only when the lines are parallel. When not in animated mode, there is a button that alternates the two pairs of angles. The text on the page discusses the properties of the angle pairs both in the parallel and non-parallel cases.

The page can be enlarged to full-screen size for use with a classroom projector. After use in the classroom, students can access it again from any web browser at home or in the library with no login required.

Related NY State Academic Standards: 7.G.5, 8.G.1.a, 8.G.1.c, and more!

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