Work out nonagon area instantly with clear inputs, formula shown and shareable results.
A regular nonagon has 9 equal sides. Splitting it into 9 isosceles triangles from the centre gives A = 9s² / (4·tan(π/9)), which evaluates to (9/4)·cot(π/9)·s² ≈ 6.181824·s².
Area
A = 9s² / (4·tan(π/9)) = (9/4)·cot(π/9)·s² ≈ 6.181824·s²
Apothem
a = s / (2·tan(π/9))
(9 − 2) × 180° / 9 = 140°.
Yes. For an irregular nonagon use the shoelace formula on its vertex coordinates instead.