we have already prooved that pi is the area of the unit disk and pi=2(integral from -1 to 1) square root(1-x^2) dx...use properties of the integral to compute the following in terms of pi

a. (integral from -3 to 3) square root (9-x^2) dx

b. (integral from 2 to 0) square root (1- 1/4 x^2) dx

c. (integral from -2 to 2) (x-3) square root (4-x^2) dx

im sorry about the poor notation, but i have no other idea how to write it.....i appreciate any help whatsoeever and thanks in advance.