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finding the volume of a cylinder is actually very similar to finding the volume of a box. The volume of a box is base*width*height... but if you pay attention base*width is just the area of the bottom rectangle. So we want to take the area of the bottom shape and multiply it by height. The bottom shape is a circle. The area of a circle is (pi)*radius^2 so the volume of the cylinder is height*(pi)*radius^2. Which is normally written as (pi)(r^2)h.

Ok for a volume of a pyramid, the idea, is again similar to solving for a box. We take the base of the shape and multiply it by the height. The base of a pyramids is a square which is calculated with base*width. So its base*width*height. But that's the equation for a box! What happened? Well the thing to note is that the subtle difference is the pyramid is calculated the same was as the box, but it's only 1/3rd of the box's size. So how do we correct for this? Just do base*width*height*1/3. so its written as 1/3(b*w*h).