What is the length of the unlabeled side?
a- 5 in
b- 7 in
c- 16 in
d- 25 in

In order to solve this, we will need to use Pythagoras' Theorem:



However, since we are trying to find the shorter side, we need to rearrange the formula:



In this case, c = 13in (hypotenuse)  
                    b = 12in

Sub these values to find a,


= 25

Square root both sides to get 'a' on its own,

a = 5

Therefore, the unknown side is 5in!

Hope this helped! Ask me if there's any part of the working you don't understand :)