To calculate the area of a regular pentagon, the perimeter of the polygon is multiplied by the apothem and the result is divided in half. The mathematical formula for the calculation is area = (apothem x perimeter)/2.
A regular pentagon means that all of the sides are identical and all angles are the same as each other. To calculate the area, the length of one side needs to be known. Also, the length of a line from the middle of a side to the middle of the pentagon is needed. This line is known as the apothem, which is also the radius of the intercircle that can be drawn within the pentagon.