Joel is laying pipe for a sprinkler system before he plants his lawn. The lawn is rectangle, 15 feet long and 8 feet wide. He needs to lay a piece of pipe that will run along the diagonal of the lawn. It will divide the area of the lawn into two right triangles. What will be the length of the pipe?

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.