
Timothy H. answered 05/09/20
Patient and Knowledgeable SAT Math, Calculus, Geometry Tutor
Hi Darren,
The question does appear tricky, but recall the formula for one revolution of a circle: 2πr.
Now imagine you took each revolution and added it up: 2π(summation of radii)
In other words, 2π∫04(x+1)dx is a revolution around the x-axis
and 2π∫03(y-1)dy a revolution around the y-axis. Once you evaluate the integrals, you should have your solutions.