check the picture below.
notice, the figure is just, a triangle with a base of 3 and an altitude of 4, a rectangle of 4x7, and a semi-circle with a diameter of 4.
[tex]\bf \textit{area of a circle}\\\\
A=\pi r^2\qquad
\begin{cases}
d=diameter\\
r=radius=\frac{d}{2}\\
-------\\
d=4\\
r=2
\end{cases}\implies
\begin{array}{llll}
A=\pi 2^2\implies A=4\pi\\\\
\textit{area of half that circle}\\\\
A_h=\cfrac{4\pi }{2}\implies A_h=2\pi
\end{array} \\\\
-----------------------------\\\\
\stackrel{\textit{area of triangle}}{\frac{1}{2}\cdot 3\cdot 4}+\stackrel{\textit{area of the rectangle}}{4\cdot 7}+\stackrel{\textit{area of the semi-circle}}{2\pi }
\\\\\\
6~~+~~28~~+~~2\pi[/tex]
