the area of a circle is calculated by multiplying pi times the squared radius, and the diameter is equal to 2 radius, so we have that the diameter is 8 in, therefore half of it is equal to the radius, that is:
radious = r = diameter/2 = 8/2
r = 4 in
then we express the area equation:
a = pi*r^2
a = (3.14)*(4)^2
where we have substituted pi = 3.14 and radious, r = 4
a = (3.14)*(16)
a = 50.24
therefore the area is 50.24 squared inches