Answer:
In a right angled triangle, length of hypotenuse is calculated by using the formula :
[tex]Hypotenuse^{2}= \sqrt{Base^{2} + Perpendicular^{2} }[/tex]
Now, there could be a possibility that the term under square root does not form a complete square, then an approximation of the root will make more sense in calculating the length of hypotenuse.
For real-world problems, you would want an approximation, so that you will have an estimate of the length you are looking to find out.