we know that
the area of the ground covered by the tent is a circular area
then
the area of a circle is equal to
[tex]A=\pi r^{2}[/tex]
Step [tex]1[/tex]
Find the radius of the circular base
we know that
in the right triangle ABC-----> see the attached figure to better understand the problem
[tex]tan\ 70=\frac{r}{12}[/tex]
Solve for r
[tex]r=12*tan\ 70[/tex]
Step [tex]2[/tex]
Find the area of the base
substitute the value of the radius in the formula of area
[tex]A=\pi r^{2}[/tex]
[tex]A=\pi*(12*tan\ 70)^{2}\ ft^{2}[/tex]
therefore
the answer is the option a
the area of the ground covered by a conical tent is equal to
[tex]A=\pi*(12*tan\ 70)^{2}\ ft^{2}[/tex]