Evaluate the integral below by interpreting it in terms of a partial circle area. In other words, draw a picture of the region the integral represents, and find the area using high school geometry.
-9 to 9 sqrt(81-x^2)dx
The first thing you want to do is make a u substitution.
Let u=2x+1
then du=2dx
or dx=(1/2)du
Re-evaluate your limits plugging in zero you get 1 and plugging in 1 your get 3.
So you have:
