This problem, the elementary school mathematics knowledge is not enough, and there is no arc system to express the angle, so the solution will be more troublesome and not concise.

The final area is converted into a decimal, which is about 3.847?

The previous answer was 6.28, which was completely wrong. The area of the small semicircle in the figure is (1/2)×pi × 2×2, which is about 6.28.