What is the area of a 15-gon with a perimeter of 90 m

Assuming a regular polygon, then s = 90/15=6

A 15 - gon has exterior angles = 360/15=24, so interior angles of 156

Form a triangle with a radius, apothem and a half - side

Then the 156/2 = 78 degrees, with the apothem being opposite, and the halfside being adjacent = 3

so tan 78 = a/3 and a = 3tan 78=14.114

Then area = (1/2) Pa = (1/2) (90) (a) = 635.13 m^2