You can put this solution on YOUR website! Pythagorean problem.
Consider a right angled triangle.
Upright side = 40ft
Base = 24ft
Hypotenuse (Diagonal) = ?
40ft^2 + 24ft^2 = Diagonal^2
Diagonal^2 = 1600 + 576
Diagonal = square root of 2176
Diagonal = 46.7ft.
Hope this helps.
:-)