check the picture below.
if ∡F = 90° and ∡D = 30°, then the ∡A = 60°, meaning the triangle is a 30-60-90 triangle and therefore we can use the 30-60-90 rule as you see in the picture.
[tex]\bf \textit{area of a triangle}\\\\
A=\cfrac{1}{2}bh~~
\begin{cases}
b=base\\
h=height\\[-0.5em]
\hrulefill\\
h=7\sqrt{3}\\
b=7
\end{cases}\implies A=\cfrac{1}{2}(7)(7\sqrt{3})
\\\\\\
A=\cfrac{49\sqrt{3}}{2}\implies A\approx 42.43524478543749369142[/tex]
