Geometry and TrigonometryVery hardSides of a regular polygon from an exterior angle
Geometry and Trigonometry practice question
Each exterior angle of a regular polygon measures 20°. How many sides does the polygon have?
Answer: 18
The exterior angles of any polygon add to 360°, so the number of sides is 360/20 = 18.
Common wrong answers
- If you answered 9
- 9 uses 180 instead of 360.
- If you answered 16
- 16 comes from (n − 2)·180 = 20n, a mix-up with interior angles.
- If you answered 20
- 20 copies the angle.
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