Question 793226: a regular pentagon I inscribed in a circle whose radius is 9 in. find the area of the pentagon Answer by KMST(5328) (Show Source):
You can put this solution on YOUR website! Here is your pentagon (in red), with the circle, and the radii to the pentagon vertices (in green). Those radii split the pentagon into 5 congruent isosceles triangles.
The area of a triangle can be calculated as if you know the measures of sides and and angle between those two sides.
In this case, two of the sides are the radii, measuring , and the angle between them measures .
The area of one of those triangles is = approx. =
The area of the pentagon is approximately
