The shaded region is the area of the circle minus the area
of the pentagon.
A circle = pi * r^2
A circle = pi * 15^2
A circle = 706.5 cm^2
A regular pentagon = (a * p)/2 where a is the apothem, p is the perimeter.
The apothem id the perpendicular height from the midpoint of a side to the center of the pentagon.
To find the apothem you have to use a trig ratio.
A pent = (8.3 * 12*5)/2
A pent = 249 cm^2
Shaded region: circle - pentagon 706.5 - 249 = 457.5
