1. SECTION 8.1 Angles of
Polygons

2. ANGLES OF POLYGONS
 How do I find the sum of the measures of the interior angles
of a polygon?
 How do I find the sum of the measures of the exterior angles
of a polygon?

3. CLASSWORK
 Complete Polygon Angle Sum Worksheet

4. INTERIOR ANGLE SUM THEOREM
 Theorem 8.1 – If a convex polygon has n sides and S is the
sum of the measures of its interior angles, then
S=180(n-2)
 What is the sum of the interior angles of a octagon?

5. INTERIOR ANGLE SUM
 Interior Angle Sum = # of angles * measure of one interior angle

6. EXAMPLES
 The measure of an interior angle of a regular polygon is 135.
Find the number of sides in the polygon.
 Find the measure of each interior angle.
S T
R U

7. EXTERIOR ANGLE SUM THEOREM
 Theorem 8.2 – If a polygon is convex, then the sum of the
measures of the exterior angles, one at each vertex, is 360.

8. EXAMPLE
 Find the measure of an exterior and an interior angle for the
figure.

9. HOMEWORK
 Page 407
 14 - 40 Even
 43 and 44

10. LESSON PLAN
 Intro
 This chapter is all about Quadrilaterals. First we need to work on
figuring out the measures of interior and exterior angles in a polygon.
 Standards- 8.1 (Power)
 Supplies – slides, whiteboard, handout, rulers, protractors and
book
 Timing - 1 day (block), 1 review day and a quiz
 Essential Questions- slide 2
 Input – slides 4 and 6
 Guided Practice – slides 4, 5 and 7
 Independent Practice – Bookwork