If the measure of the interior angle of a regular polygon is 90° greater than the measure of its exterior angle, then how many sides does it have?
If the measure of the interior angle of a regular polygon is 90° greater than the measure of its exterior angle, then how many sides does it have? Correct Answer 8
Given:
Interior angle = Exterior angle + 90°
Concept used:
Interior angle + Exterior angle = 180°
Formula used:
Number of sides of the polygon = (360°)/(Exterior angle)
Where,
n = number of sides of the polygon
E = Exterior angle
I = Interior angle
Calculation:
According to the question,
Interior angle = Exterior angle + 90°
⇒ I = E + 90° ----(1)
We know that,
⇒ I + E = 180°
From equation (1)
⇒ E + 90° + E = 180°
⇒ 2E = 90°
⇒ E = 45° ----(2)
Now,
Number of sides of the polygon = (360°)/(Exterior angle)
⇒ n = (360°/45°)
⇒ n = 8
∴ The regular polygon has 8 sides.
Additional Information
1) Regular Polygon: If all sides of any polygon are equal, the polygon is called a regular polygon.