Three circles of radius 4 cm are kept touching each other. The string is tightly tied around these three circles. What is the length of the string?

Answer: Option A

Solution

Answer: Option A

Solution:

$$\begin{array}{rl}& =3\times 2\sqrt{Rr}\\ & =3\times 2\sqrt{4\times 4}\\ & \\ & =24\\ & \\ & =24+2\pi r\\ & =24+2\pi \times 4\\ & =24+8\pi \text{ cm}\end{array}$$