To determine the area of the figure you have to decompose it into two simpler figures:
A semicircle (green) and a rectangle (blue)
The total area of the figure is equal to the area of the semicircle plus the area of the rectangle
The area of the rectangle can be calculated as
The area of a circle can be calculated as
To calculate the area of the semicircle you have to divide it by 2
The semicircle has a diameter of d=6
So the radius is
The area of the semicircle is
Finally add both areas to determine the area of the figure
The total area of the figure is 86.1