Area of Pentagon

A Pentagon is a five-sided polygon in geometry. It may be simple or self – intersecting in shape. The five angles present in the Pentagon are equal. A regular pentagon has all of the sides and angles are the same as each other. Pentagons can be regular or irregular and convex or concave. A regular pentagon is one with all equal sides and angles. Its interior angles are 108 degrees and its exterior angles are 72 degrees. An irregular pentagon is a shape that does not have equal sides and/or angles and therefore does not have specified angles. A convex pentagon is one whose vertices, or points, where the sides meet, is pointing outwards as opposed to a concave pentagon whose vertices point inwards. Imagine a collapsed roof of a house. Now, the Pentagon area is derived by multiplying side and apothem length with (5/2). 
The Area of a Pentagon Formula is,

A = (5 ⁄ 2) × s × a
Where,

“s” is the side of the Pentagon and
“a” is the apothem length.