Question 874124
I think you mean y^2 + 20^2 = 29^2 (otherwise, y = 9, according to what you typed).


If y^2 = 20^2 = 29^2, then y^2 = 29^2 - 20^2 = 841-400 = 441, and y = +/- 21. In the context of a geometry problem or any problem involving physical lengths, y would equal +21.