Question 134793
use Pythagorean theorem
{{{a^2 + b^2 = c^2}}}
in this case, you are given the hypotenuse and one leg. 
So, c = 45 and a = 27.

Plug in and solve for b and that is your answer
{{{b^2 = c^2 - a^2}}}
{{{b^2 = 45^2 - 27^2}}}
{{{b = sqrt(45^2-27^2)}}}
b = 36

notice the ratio of the sides --> 3:4:5  that is a common ratio in these types of problems. Keep an eye out for them :)