Interior Polygon Angle Measures Practice I
Name_____________________
Write the FORMULA for:
The sum of the measures of the interior angles of a polygon:
The measure of each interior angle of a regular polygon:
Find the sum of the measures of the interior angles of the convex polygon using the formula.
Show all work.
1) 10-gon
2) 12-gon
3) 15-gon
4) 18-gon
5) 20-gon
6) 30-gon
7) 40-gon
8) 100-gon
Find the value of x. First, find the sum of the polygon. Second, set up the equation. Third,
work out the equation.
Example:
Interior angle sum: 540o (bc it is a pentagon with 5-sides)
Equation: x  130  90  113  80  540
x  130  90  113  80  540
Work: x  413  540
x  127
9)
10)
11)
Interior angle Sum _______
Interior angle Sum _______
Interior angle Sum _______
Equation:
Equation:
Equation:
Work:
Work:
Work:
12)
13)
14)
Interior angle Sum _______
Interior angle Sum _______
Interior angle Sum _______
Equation:
Equation:
Equation:
Work:
Work:
Work:
15)
16)
17)
Interior angle Sum _______
Interior angle Sum _______
Interior angle Sum _______
Equation:
Equation:
Equation:
Work:
Work:
Work:
18) A convex quadrilateral has interior angles that measure 80°, 110°, and 80°. What is the
measure of the fourth interior angle?
19)
A convex pentagon has interior angles that measure 60°, 80°, 120°, and 140°. What is the
measure of the fifth interior angle?
You are given the measure of each interior angle of a regular n-gon. (Remember that special
formula that Mrs. James made up!?) Find the value of n.
20) 144°
21) 120°
22) 140°
23) 108°
24) 156°
25) 157.5°