Answer: 12
Step-by-step explanation:
For this question you would have to use pythagoras' theorem.
The formula to work out the shorter side is a²=c²-b² so for this question it would be a²=13²-5² when you put the numbers in the formula.
13²=169
5²=25
a²=169-25
a²=144
Then to work out a on it's own you would square root 144.
The square root of 144 is 12.
