8-4 Angles in Polygons
The sum of the measures of the angles in a triangle is 180 degrees.
8-4 Angles in Polygons
Solve for x:
1)
2)
79o
(x+20)o
37o
x
40
o
57o
1
8-4 Angles in Polygons
Solve for x:
3)
34o
70o
x
8-4 Angles in Polygons
Concave
Regular
-All sides congruent
Convex
Irregular
-Everything else !!!
-All angles congruent
2
8-4 Angles in Polygons
Divide each polygon into triangles to find the sum of its angle measures:
5)
4)
8-4 Angles in Polygons
# of Sides
Name of Polygon
Interior Angle Sum
3
4
5
6
7
8
9
10
11
12
3
8-4 Angles in Polygons
6)
Give the technical name for each polygon pictured:
regular
convex
octagon
irregular
convex
pentagon
8-4 Angles in Polygons
7)
Give the technical name for each polygon pictured:
irregular
concave
decagon
regular
convex
pentagon
4
8-4 Angles in Polygons
Angle Sum = (n-2)(180)
Divide each polygon into triangles to find the sum of its angle measures:
9)
8)
8-4 Angles in Polygons
Find the measure of the 3rd angle in each triangle, then classify the
triangle as acute, obtuse, or right:
10)
94o, 28o
11)
66o, 73o
5