Trigonometry
posted by Zayn .
A standard doorway measures 6 feet 8 inches by 3 feet. What is the largest dimension that will fit through the doorway without bending?

You are looking for the diagonal, let it by x
x^2 = (20/3)^2 + 3^2 = 481/9
x =√(481/9) = appr 7.31 ft
or appr 7 feet 3 inches