Download 8.1 Angle Measures in Polygons 1. In the following polygons, name

8.1 Angle Measures in Polygons
1. In the following polygons, name each polygon.
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2. Divide each polygon into triangles by drawing lines from one vertex. One of them has been done for you.
3. If each triangle’s interior angles adds up to 180o, how many degrees does each type of polygon have? Complete the
chart.
Polygon Name
Number of Sides
Number of Triangles
4. What is the relationship between the number of sides and the number of triangles?
Total interior angle degrees
So, in general, we can say that if a polygon has n number of sides then to find the total degrees of the interior angles is
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Example:
1.
The sum of the measures of the interior a convex polygon is 900o. Classify the polygon by the number of sides.
2.
The coin shown is the shape of a regular 11-gon. Find the sum of the measures of the
interior angles.
3.
The sum of the measures of the interior angles of a convex polygon is 1440o. Classify
the polygon by the number of sides.
Example with Algebra.
So what about the exterior angles?
Examples
Fact: An interior angle + an exterior angle = _____________________
A regular n-gon has an interior angle measure of about 158.82o. How many sides does the polygon have?