Geometry Benchmark Trouble!?

Area=1/2 apothem x perimeter
how do you find the apothem of a regular pentagon with a radius of 8 feet. Also, I cant seem to figure out how to find the side length either, so help with that would be useful.
Best Answer goes to first person to respond with the answer, and all help is much appreciated (If i cant pass benchmark, Ill have to retake the course next year!)

Ed I2012-04-29T16:41:42Z

Favorite Answer

Let a = apothem and s = length of side

a/8 = sin 36°
a = 8 sin 36° ≈ 4.702

(s/2)/8 = cos 36°
s = 16 cos 36° ≈ 9.405