Wow there's a lot of questions there.
Pythagorean Theorem states that in a right triangle, the
hypotenuse^2 = leg1^2 + leg2^2
If the hypotenuse isn't known use the above formula.
If a leg isn't known, use
hypotenuse^2 = leg1^2 + leg2^2
leg1^2 = hypotenuse^2 - leg2^2
