Semicircle

The ornament consists of one square and four dark semicircles. The area of the square is 4 cm ^ 2. Find the area of one dark semicircle and round the result to hundreds.

Correct answer:

S =  1.57 cm²

Step-by-step explanation:

$$\begin{gathered} S_1=4{\text{cm}}^2 \\ {S}_1=a^2 \\ a=\sqrt{S_1}=\sqrt{4}=2\text{ cm } \\ a=2\cdot r \\ r=a\mathrm{/}2=2\mathrm{/}2=1 \\ S={\displaystyle \frac{1}{2}}\cdot \pi \cdot r^2={\displaystyle \frac{1}{2}}\cdot 3.1416\cdot 1^2=1.57{\text{cm}}^2 \end{gathered}$$

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