Answer:
h = 9 ft
Step-by-step explanation:
Assume the diagram is like the one below.
∆ABD is a right triangle.
We can use Pythagoras' Theorem to find the height h.
[tex]\begin{array}{rcl}h^{2} + 40^{2} & = & 41^{2}\\h^{2} + 1600 & = & 1681\\h^{2} & = & 1681 - 1600\\& = &81\\h& = & \sqrt{81}\\&=& \mathbf{9}\end{array}\\\text{The height of the gable is $\large \boxed{\textbf{9 ft}}$}[/tex]
