Question

can anyone tell the steps to take out the correct answer?

Answer 1

radius of biggest circle is 3x cm.
a) so circumference
$2\pi \times 2x \: \: cm = \: 4\pi \times x \: \: cm$
b)required circumference in this case
=
$(\pi \times 2x + \pi \times x) \times 2 = 6\pi \times x \: \: cm$
$similarly \: area \: of \: the \: shaded \: region \: = \\ (\pi \times {2x}^{2} \times \frac{1}{2} - \pi \times {x}^{2} \times \frac{1}{2} ) \times 2 \\ = 3\pi \times {x}^{2} \: {cm}^{2}$
hope you get your answer.