Regular Polygon
(area, apothem, peak angle)
Formulae:
no. of diagonals : n(n-3)/2 where n is the no. of sides
Peak angle (in degrees ) : 180(1 - 2/n)
Area: na2 /4tan(180/n) where 180/n is in degrees & a is length of each side
Apothem: a/2tan(180/n) ; where apothem is the perpendicular bisector from center to a side
Circum-radius: apothem*sec (π/n)