Ineed on finding the length of diagonal le.

A²+b²=c²

8²+b²=17²

64+b²=289
subtract 64 from both sides

b²=225
find the square root of both sides to isolate b

b = 15

15*2

LE = 30ft

The quadrilateral is composed of 4 right angle triangle. By use of Pythagoras, you can find the length of LE. I will use the the triangle with the 20 and half of LE as legs and 25 as the hypotenuse. So 20^2 + x^2 = 25^2. With that equation, you can find that x = 15, but x only represents half of LE. So you have to multiply x by 2 and you will find that the length of LE is 30.