Polygons & Angle Sums
Interior angles of an n-sided polygon add to (n − 2) · 180°.
The rules
- A regular polygon has equal sides and angles.
- Each interior angle of a regular n-gon is (n − 2) · 180 / n.
- Exterior angles of any polygon add to 360°.
- Count the sides first.
Watch out: Using n · 180 instead of (n − 2) · 180.
Worked example
What is each interior angle of a regular hexagon?
- Sum = (6 − 2) · 180 = 720.
- 720 / 6 = 120.
Answer: 120°
Try it yourself
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