Math

Decagon Calculator

Find the area and perimeter of a regular decagon (10 sides).

Calculated Output

Area 192.36

Perimeter 50

Formula: area = (10/4)·s²·cot(π/10)

Step-by-Step Breakdown

1. Values used:

2. Side length = 5

4. Area = 192.36

5. Perimeter = 50

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The math behind it

Area = (n/4)·s²·cot(π/n) with n = 10.

Side 5 → area ≈ 192.36, perimeter 50.

What is the sum of its interior angles?

(10 − 2) × 180° = 1440°.