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Geometry
January 17, 2017
6.1 Polygon Angle Sum Theorem
DO NOW
1. How many degrees are in a triangle?
2. How many degrees are in a square?
3. Calculate 5 − 2 ⋅ 180
4. Calculate
7−2 ⋅180
7
Agenda
• Announcements (2nd hour only)
• Do Now
• Exercise: Polygon Angle Sum Theorem
• Notes: PAST
• Practice
I can use properties of
polygons and classify
quadrilaterals.
PAST Exercise
Key Terms!
Concave: At least one interior angle is reflex
Convex: No interior angles are reflex
Key Terms!
Regular polygon: All sides are congruent, all
angles are congruent.
Polygon Angle Sum Theorem
The sum of the interior angles of a convex
polygon with 𝑛 sides is 𝑛 − 2 ⋅ 180°
Each interior angle of a regular polygon with
𝑛 sides is
𝑛−2 ⋅180°
𝑛
Polygon Exterior Angle Sum Theorem
The sum of the exterior angles of a convex
polygon with 𝑛 sides is 360°
Each exterior angles of a regular polygon
with 𝑛 sides is
360°
𝑛
Practice
p. 356 7-25 odds