We can see a right triangle here. Diagonal is a hypotenuse of the right triangle. Two legs are equal 102 yards each. We can use Pythagorean theorem hypotenuse² = leg² + leg² = 2leg² hypotenuse² = 2leg² √hypotenuse² = √(2leg²) hypotenuse = leg*√2 hypotenuse = 102*√2≈144.25 yards