Odd rounded pyramid shape - how to calculate shape/size?
I am trying to figure out the "equation" or other means of finding the exact shape in the figure below. It's somewhat of a pyramid with a rectangular base, but the sides are curved rather than flat. I have found how to make the longer sides (simple half-circle) but the narrow two sides I can't quite figure out. The long edge is 40" and the shorter edge is 30".
Can anyone tell me exactly how to calculate the measurements/curves of the narrower side (third picture)?
NOTE: The narrow side in the third picture is really just a trial-and-error cut-out, no measurements or calculations were done to determine what it should look like.