Semicircle

The ornament consists of one square and four dark semicircles. The area of the square is 4 cm². Find the area of one dark semicircle and round the result to hundreds.

Correct answer:

S =  1.57 cm²

Step-by-step explanation:

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

Try another example