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  1. The exterior angle of a regular polygon is 20°. Homework Help ✎

    1. What is the measure of an interior angle of this polygon? Show how you know.

    2. How many sides does this polygon have? Show all work.

The interior and exterior angles are supplementary.

Refer to the Math Notes box in Lesson 8.2.2.

The sum of the measures of the exterior angles is 360°.