Question

what is the approx. length of the door

Answer 1

the approximate length of the door with be
c) 84 inches

Answer 2

$\sqrt{ { d}^{2} - {w}^{2} } = l$

$\sqrt{ {94}^{2} - {42}^{2} } = l$
root under
8,836-1,764
root under
7072
so answer is
84.