[tex]\bf \textit{area of a trapezoid}\\\\
A=\cfrac{h(a+b)}{2}\quad
\begin{cases}
a,b=\stackrel{parallel~sides}{bases}\\
h=height\\
--------\\
A=72.8\\
a=7.4\\
b=10.8
\end{cases}\implies 72.8=\cfrac{h(7.4+10.8)}{2}
\\\\\\
72.8=\cfrac{18.2h}{2}\implies \cfrac{72.8\cdot 2}{18.2}=h[/tex]
