Are you sure you mean "squaring the triangle"? The only reference I can find to this concept is in a rather obscure article about insurance underwriting, and there it's meant euphemistically. All other references are pure geometry.
There is the arcane concept of "squaring the circle," which does appear as a metaphor for trying to do the impossible. Apparently, in centuries gone by, thinkers of all types (mathemeticians, philosophers, alchemists) tried to find a geometric way to construct the area of a circle and so to calculate it exactly. This, we now accept, is not possible.
thanks for the replies. I surely did mean for a non geometrical context, even though it really started from a mathematical book containing an article on squaring a triangle. Google couldnot put me something useful, hence asked for it here.