Degree

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Name _

______________________

What’s My Degree?

Regular Polygon

Shape

Name of

Polygon

Number of

Sides

Number of triangles

Sum of Interior

Angles

Measure of one angle

What is the rule or formula for finding the sum of the measures of the interior angles of a polygon?

Rule:

What is the rule or formula for finding the measure of an interior angle of a regular polygon?

Rule:

There are two types of problems that arise when using this formula:

1. Questions that ask you to find the number of degrees in the sum of the interior angles of a polygon.

2. Questions that ask you to find the number of sides of a polygon.

Hint:

When working with the angle formulas for polygons, be sure to read each question carefully for clues as to which formula you will need to use to solve the problem. Look for the words that describe each kind of formula, such as the words sum, interior, each, exterior and degrees.

Example 1:

Find the number of degrees in the

sum

of the

interior

angles of an octagon.

An octagon has 8 sides. So

n

= 8. Using the formula from above,

180(n - 2)

= 180(8

- 2) = 180(6) =

1080

degrees.

Example 2:

How many sides does a polygon have if the

sum

of its

interior

angles is 720°?

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