Let's solve step by step
First, remember: in a regular polygon, the exterior angles all have the same size. The exterior angle shown is 120 degrees.
In any polygon, the exterior angle and the interior angle add up to 180 degrees. So the interior angle here is 180° − 120° = 60°.
For a regular polygon, the sum of all exterior angles is always 360 degrees. If each exterior angle is 120 degrees, we can find how many sides the polygon has by dividing:
- Sides count n = 360° ÷ exterior angle = 360° ÷ 120° = 3.
So the polygon is a triangle (3 sides). All sides have length 5 units, and the perimeter is the total length around the shape:
- Perimeter = number of sides × side length = 3 × 5 = 15 units.
Answer: 15 units