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7.1 pgs. 359-366
EQ: What is the sum of the measures of the interior angles of a polygon?
Date:
Polygon (Interior) Angle Sum Theorem
Example: Finding a Polygon Angle Sum Find the sum of the measures of the angles each polygon without drawing the polygon or triangles. a. b. decagon c. 15 - gon Example: Using the Polygon Angle Sum Theorem Find m∠R in pentagon TVYMR at the right. m∠R = ______ Example: Solving for the Number of Sides (working backwards). Given the sum of the interior angles of a polygon, determine the number of sides. a. 720° b. 2160° c. 3420° Example: Finding the Measure of Each Interior Angle in a Regular Polygon. a.Find the measure of each interior angle in a regular pentagon. b. Find the measure of each interior angle in a regular polygon with an interior angle sum of 1800°.
V
135°
R
T
M
Y
2x
2x
75°
421e Let n ofsides
The sum of the interior anglesof a convex polygon are 180 Ch Z
sides 2 180
in
6sides DSides2 10 2 8 Ss 213Is4triangles 84803 14400
411801 7200 134801 23400
21605sides
Eimagessuo
30044 240 1200X 60
8 4 triangles 12triangles 19triangles2 t22
sides 14sides 21sides
108
C ios 108
5 sides 348055400 5412 5angles 108 108
3triangles angffsmiontsides 1080
funny1800010TrianglesSILFIES boo
angles foreaangle
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HW: Polygon Interior Angles Practice
Is the figure a polygon? If not, say why not.
1. 2. 3. 4.
Name each polygon. Then identify all the sides and angles.
5. 6.
Classify each polygon.
7. 8. 9. 10.
Find the sum of the interior angles of the polygon.
11. 12. Dodecagon 13. 16-gon 14. 100-gon
Find 𝑥 and m� P.
15. 16.
Find the measure of each interior angle in the regular polygon.
17. 18. Octagon 19. Nonagon 20. 20-gon
Name: ______________________________
Date: __________________ Period: ______
M
A
T
H
Name: _______________
Sides: _______________
Angles: _____________
R G
T E A
Name: _______________
Sides: _______________
Angles: _____________
67° 151°
95° 144°
𝑥° 𝑃 170°
162°
95° 18𝑥°
11𝑥°
𝑃
21. Given the sum of the interior angles of a regular polygon of 1620° , determine the number of sides.
22. Find the measure of each interior angle of a regular polygon with an interior angle sum of 6120°
2121