Work out pentagon area instantly with clear inputs, formula shown and shareable results.
A regular pentagon has 5 equal sides. Splitting it into 5 isosceles triangles from the centre gives A = 5s² / (4·tan(π/5)), which evaluates to ¼√(5(5+2√5))·s² ≈ 1.720477·s².
Area
A = 5s² / (4·tan(π/5)) = ¼√(5(5+2√5))·s² ≈ 1.720477·s²
Apothem
a = s / (2·tan(π/5))
(5 − 2) × 180° / 5 = 108°.
Yes. For an irregular pentagon use the shoelace formula on its vertex coordinates instead.