1. The problem statement, all variables and given/known data At my old university, Calculus was taught much differently than it is where I am now. My old school focused on numerical things, which this school focuses much more on pictures, abstract, etc. and it's very difficult for me. At my old school, we were given a shape, bounded by functions, and told to build a Riemann sum for area and make it an integral. Now, I'm given shapes that aren't described at all by functions. They are just shapes. Right now they are slicing them into rectangular partitions, but it's hard for me to find a way to describe the other part of the rectangle (that isn't delta x, h, w, whatever.) 2. Relevant equations 3. The attempt at a solution Construct a Riemann Sum and integral for a circle of radius 3 using horizontal partitions. So, the height of the partition is delta h, and the width of the partition is completely unknown. My assumption is that I find it by not looking at the partition, but at the actual SHAPE created when h is at a set point, IE, finding a way to express w in terms of h. But how on a circle? w should get smaller the further I am from the center of the circle in either direction, so w grows, to a max of 3, and then shrinks to 0 again. How do I make this into actual math?