In the theorem, a^2+b^2=c^2, and c equals the longest side (in this case, hypotenuse). The known leg can be a. So now, we can substitute and our equation is 36+b^2=144. Subtract 36 from both sides, & b^2=108. Depending on what form the problem wants you to answer with, the answer could be 6√3, 10.39230484
..., or the decimal simplified.
