By: Tom Capra

1
Sum of Interior Angles

• By Tom Capra

2
Table of Contents

• Standards Addressed
• Class Notes
• Formulas
• Examples
• Conclusion

3
New Jersey Core Curriculum Contents Standards

• STANDARD 4.2 (GEOMETRY AND MEASUREMENT)
• All Students will develop spatial sense and the
  ability to use geometric properties,
  relationships, and measurement to model, describe
  and analyze phenomena

4
Rules of Polygons

• Test 1 Is the symbol made up of straight line
  segments only?
• Test 2 Does each line segment in the symbol
  intersect exactly two other line segments, one at
  each end point?

Non-Polygon
Polygon
Non-Polygon
Polygon
5
Review of Polygons
Triangle
Hexagon
Quadrilateral
Pentagon
6
Class Notes
7
Number of Triangles

• Measure of any Triangle is 180
• Draw diagonal from only 1 endpoint
• Cannot draw diagonals to adjacent sides

1 Triangle 180
2 Triangles 360
3 Triangles 540
8
Formula Page

• Theorem- Polygons Interior Angle Theorem
• Sum of the measures of the interior angles of a
  convex polygon is
• (n-2) x 180

9
Examples
1. Solve for x.
2. What is the sum of the interior angles of a
22-agon?
120
(n-2) x 180 (22-2) x 180 20 x 180 3600
X
135
135
(n-2) x 180 (6-2) x 180 4 x 180
720 9013513590x120720 570x720 X150
10
Conclusion

• Homework
• Pg. 196 1-23 odd, 35 43
• Quiz on Wednesday 12/12