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8-1 day 2Objective: I will investigate the measures
of the interior and exterior angles of polygons
Find the sum of the measures of the interior angles of each convex polygon
A. 32-gon B. 18-gon C. 19-gon
D. 27-gon E. 4y-gon F. 2x-gon
Use the formula (n-2)180 to find the SUM of the INTERIOR angles of a convex polygon
Find the measure of each interior angle
An exterior angle is formed when one side of the polygon is extended at each vertex.
Note: the measure of one interior plus one exterior always equals 180 degrees because they are a linear pair!!!
What is an exterior angle???
Investigating Polygons
Exterior Angle sum example
What is the measure of each exterior angle of a regular pentagon?
1. What is the measure of each exterior angle of a regular decagon?
2. What is the measure of each exterior angle of a regular octagon?
3. What is the measure of each exterior angle of a regular heptagon?
4. What is the measure of each exterior angle of a regular 18-gon?
So… if the exterior angles always have a sum of 360 degrees try to answer these questions.
If each exterior angle of a regular polygon has a measure of 45 degrees. How many sides does the polygon have?
If each exterior angle of a regular polygon has a measure of 15 degrees. How many sides does the polygon have?
If each exterior angle of a regular polygon has a measure of 20 degrees. How many sides does the polygon have?
If each exterior angle of a regular polygon has a measure of 36 degrees. How many sides does the polygon have?
If an interior angle of a regular polygon has a measure of 157.5 degrees, how many sides does the polygon have?
If an interior angle of a regular polygon has a measure of 135 degrees, how many sides does the polygon have?
If an interior angle of a regular polygon has a measure of 60 degrees, how many sides does the polygon have?
If an interior angle of a regular polygon has a measure of 144 degrees, how many sides does the polygon have?
*** remember that one interior plus one exterior = 180
Homework: practice worksheet