Geometry and TrigonometryMediumInterior angle of a regular pentagon
Geometry and Trigonometry practice question
A garden bed is shaped like a regular pentagon. What is the measure of each of its interior angles?
- A. 108°Correct
- B. 72°
- C. 120°
- D. 540°
Answer: A. 108°
Each exterior angle of a regular pentagon is 360/5 = 72°, so each interior angle is 180 − 72 = 108°. (Or (5 − 2)(180)/5 = 540/5 = 108.)
Why the other answers are wrong
- B. 72°
- 72° is the EXTERIOR angle.
- C. 120°
- 120° is the interior angle of a regular hexagon.
- D. 540°
- 540° is the SUM of all five interior angles.
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