We will determine the area of the shaded region as follows:
*First: We determine the area of the circle:
*Second: We determine the area of the hexagon:
**For this, we have that the internal angles of the sub triangles formed [in the hexagon] are:
**Using this, we form two straight triangles and determine the value of the base of the triangle:
**Now, we determine the area of the hexagon:
*Finally: We subtract the area of the hexagon from the area of the circle:
So, the shaded area is approximately 39.9 square feet.