Calculate area, perimeter, interior and exterior angles, and diagonal count for any regular polygon.
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Result
Area
Perimeter
30
Interior angle
120°
Exterior angle
60°
Diagonals
9
Circumradius
5
Inradius
4.33
Also in General
Geometry
The polygon calculator finds the area, perimeter, angles, diagonal count, inradius, and circumradius of any regular polygon from its side count and side length.
For a regular polygon with n sides of length s: area = (n * s^2) / (4 * tan(pi/n)). Interior angle = (n-2) * 180 / n. Exterior angle = 360 / n.
The number of diagonals is n(n-3)/2. A triangle has 0, a square has 2, a pentagon has 5, and so on.
Applies to regular polygons only (all sides and angles equal). Minimum 3 sides.
Frequently asked questions
n(n-3)/2, where n is the number of sides. A hexagon has 6(6-3)/2 = 9 diagonals.
The polygon approaches a circle. A 100-sided regular polygon is nearly indistinguishable from a circle.
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