rregular polygon, numsides=5, side leng=12
area=247.748746
inside angel=108 deg, outside angel=72deg
regular polygon area=(n/4)*side*side*tangent(beta)
n=number sides
draw lines from senter av polygon tu 2 ends av the bottom side
get isosaleez triangel & beta=its angel at the base
for n=5, beta=54 deg & tan(beta)=1.3763819205
get area av 1 such triangel, then multipli bi n