Answer:
as a semicircle, a hexagon, and a rectangle
Explanation:
The first attachment shows the decomposition according to the answer choice above. It would make area computation about as simple as it could be.
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The second attachment shows a decomposition with a circle. It leaves a very odd shape in the middle that is not easily divided into triangles, rectangles, or trapezoids.
The third attachment shows a semicircle, a pentagon, and two triangles. The pentagon is not a regular pentagon, so might require further decomposition in order to determine its area.