Question

A right triangle has one leg that is 12 units long and a hypotenuse that is 15 units long. Find the length of the other leg

Answer 1

Use Pythagorean theorm (a²+b²=c²) 
12 is either a or b 
15 is your c 
12²+x²=15²
144+x²=225
subtract 144
x²=81
square root of 81 
final answer is 9 

Answer 2

Let a be the other leg.

By the Pythagorean theorem:

$a= \sqrt{15^2-12^2}= \sqrt{225-144}= \sqrt{81}=9 \ units$