How to make the sum of three squares make a square
The product of two number, each of which is the sum of two squares, will also be the sum of two squares. (a^2 + b^2)(c^2 + d^2) = (a^2 c^2 - b^2 d^2)^2 + (a^2 d ^2 + b^2 c^2)^2. It is also the difference of two squares. (a^2 + b^2)(c^2 + d^2) = ((a^2 + b^2 + c^2 + d^2)/2)^2 - ((a^2 + b^2 - c^2 -... Sign in to see full entry.