How can you decompose the composite? ?

  as a semicircle, a hexagon, and a rectangle

Step-by-step 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.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.