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Lesson 3.5AIM: The Polygon Exterior
Angle Sum TheoremDo Now: Find the measure of Angle A.
Step 1: How many sides in the shape?
5 sides
Step 2: Sum of Interior Angles?
(n - 2)180
(5 - 2)180 = 540º
Step 3: Subtract Given Angles.
540 - 113 - 80 - 130 - 90 = 127º
The sum of the measures of the exterior angles in a polygon is
360º
The sum of an exterior and interior angle is
180º
Find the value of x.
The sum of exterior angles = 360º
x + 2x + 85 + 95 = 3603x + 180 = 360 - 180 -1803x = 1803 3x = 60º
Find the number of sides of the regular polygon with the exterior angle measure
of 60º.
a. What is the measure of one of the interior angles?180 - 60 = 120º
b. Use the polygon exterior angle theorem to find the number of sides.
360º ÷ 60º= 6 sides
Summary Question