Answer:
The circumference of a circle is modeled by C=pi*d
Based on what's given d=15
We want the area, which is modeled by A=pi*r^2
R is 7.5 since the radius is half the length of the diameter.
Square the radius. This gives you 56.25
Now times that value by pi.
The area of the circle is approximately 176. 71 units squared.