How do you calculate the area of the polygon?

If it is a regular polygon--meaning that all the sides are congruent and all the angles are congruent, then the formula for area of the polygon is A=1/2 ap Here a represents the apothem, which is the distance from the center of the polygon to the midpoint of one side. p represents the perimeter of the polygon found by multiplying one side length by the number of sides. If you only know one variable such as side length, you can find the perimeter and you can find the apothem using trigonomety.