Mr. Dean has provided you with the following diagram. See attached

Calculate the total cost of the semi-circular driveway.

area = piRsq/2 - pirsq/2

I said R = 30

r=14 and I got area =1105. 84 sqft

How do I calculate the volume ?

I have an answer but I don't get it.

V= 1105. 84 x 10/12 ( I don't get the 12) this is for the excavation.