Day 5 Problems 3408

1
Day 5 Problems 3/4/08

• Decide whether the polygon is convex or concave.
• 1. 2.
• Decide whether the polygon is equilateral,
  equiangular, or regular.
• 3. 4.

2
8.2 Angles in Polygons 3/10/08

• Interior angles Exterior Angles

3
Polygon Interior Angles Theorem

• Polygon Interior Angles Theorem
• The sum of the measures of the interior angles of
  a convex polygon with n sides is (n 2) 180.
• m 1 m 2 . m n (n 2) 180

3
2
1
4
n 6
6
5
4
Use the Polygon Interior Angles Theorem

• Find the sum of the measures of the interior
  angles of a convex heptagon.
• Solution.
• A heptagon has 7 sides. Use the Polygon Interior
  Angles Theorem and substitute 7 for n.

5
Find the Measure of an Interior Angle

• Find the measure of in the diagram.
• Solution
• The polygon has 6 sides, so the
• sum of the measures of the interior
• angles is
• Then, add the measures of the interior angles and
  set the sum equal to 720.

D
E
142
88
136
C
F
105
136
A
B
6
Interior Angles of a Regular Polygon

• Find the measure of an interior angle of a
  regular octagon.
• Solution
• The sum of the measures of the interior angles of
  any octagon is
• Since the octagon is regular, divide 1080 by 8
  to find the measure of one interior angle.

7
More Practice!!!!

• Textbook p. 420 421 45, 8 22 even.