Here, we want to get the length of the third side
Mathematically, we can get this by the use of Pythagoras' theorem
It states that the square of the length of the hypotenuse equals the sum of the squares of the two other sides
Let the missing side be s
From the diagram, we have the hypotenuse as 25 (the hypotenuse is the longest side and it is the side that faces the right angle
We have this as;