Quadrant II

Calculate the radius of the quadrant, which area is equal to area of circle with radius r = 15 cm.

Correct answer:

r₂ =  20.5 cm

Step-by-step explanation:

$$\begin{gathered} r=41\text{ cm } \\ {S}_1=S_2 \\ 4\pi r_2^2=\pi r^2 \\ 4r_2^2=r^2 \\ 2r_2=r \\ {r}_2=r\mathrm{/}2=41\mathrm{/}2=20.5\text{ cm} \end{gathered}$$

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