Calculators
Undecagon Calculator
Calculate regular undecagon area, perimeter, apothem, and circumradius from a side length locally in your browser.
Enter a side length from 0 (exclusive) to 1000000000 to see the area ((11/4) × s² × cot(π/11)), perimeter (11 × s), apothem (s ÷ (2 × tan(π/11))), and circumradius (s ÷ (2 × sin(π/11))). The calculation runs locally in your browser; your value is not uploaded or stored.
Find regular undecagon measurements without uploading anything.
Enter a side length from 0 (exclusive) to 1000000000 to see the area, perimeter, apothem, and circumradius. Everything runs locally in your browser, so your value is not uploaded or stored.
Frequently Asked Questions
Everything you need to know about this tool, how it works, and privacy.
What does the undecagon calculator show?
Enter a side length from 0 (exclusive) to 1000000000. The calculator returns the area ((11 divided by 4) times side squared times cot(pi divided by 11)), the perimeter (11 times the side), the apothem (side divided by (2 times tan(pi divided by 11))), and the circumradius (side divided by (2 times sin(pi divided by 11))). For example, a side of 5 gives area about 234.140997674, perimeter 55, apothem about 8.51421809722, and circumradius about 8.87366383221.
Which formulas does the undecagon calculator use?
It uses perimeter = 11 x s, apothem = s / (2 x tan(pi / 11)), area = (1 / 2) x perimeter x apothem (equivalent to (11 / 4) x s^2 x cot(pi / 11)), and circumradius = s / (2 x sin(pi / 11)), where s is the side length you enter. This tool covers regular undecagons with eleven equal sides and equal interior angles of about 147.273 degrees.
Which inputs are accepted?
Enter a side length greater than zero through 1000000000. Decimal values are accepted. Zero, negative numbers, non-numeric text, and values above the limit show a clear error instead of a result.
Do my numbers stay private?
Yes. The calculation and copy action run locally in your browser. CodeASystem does not upload or store the value you enter.