To find missing side lengths in right triangles we use Pythagoras' Theorem which is
a%5E2%2Bb%5E2=c%5E2
where a and b are the lengths of the short sides of the triangle and c is the length of the longest side of the triangle, (this is called the hypotenuse)
So a=8 and b=15. Putting those numbers into the equation gives
8%5E2%2B15%5E2=c%5E2
working out the numbers gives
64%2B225=c%5E2 i.e. c%5E2=289
because we need to find what c is, we need to take the square root of 289
c=sqrt%28289%29
Therefore c = 17.
the pipe needs to be 17 ft long.
