Formula for the area of a regular polygon. ... The number of square units it takes to completely fill a regular polygon. Four different ways to calculate the area are given, with a formula for each. Try this Drag ... Alter the number of sides. ... If you know the apothem, or inradius, (the perpendicular distance from center to a side.
Reason is that a square has all the aspects of a parallelogram a rectangle and a rhombus. It gets its congruent diagonals from the rectangle which is congruent
