Right Triangle Problem

I have a right triangle with side lengths 4 and 5;

I need to know whatís missing, but first I must decide

:

Is the missing side a leg or is it hypotenuse?

I know Iíll use the formula, the question is, ďWhich use?Ē

 

When given sides are legs, Iíll square and find the sum.

The longest side I then will know:____________________

 

If 5 is the hypotenuse, subtraction is the key.

Iíll square, subtract, and take the root; the answer now is ______________.