Bunuel
If circle A has 3 times the area of circle B, and circle B has one-sixth of the area of square WXYZ, what is the ratio of the area of a circle inscribed within WXYZ to that of the area of circle A?
A. \(\frac{\pi}{12}\)
B. \(\frac{\pi}{6}\)
C. \(\frac{\pi}{2}\)
D. \(\frac{2}{\pi}\)
E. \(\sqrt {12\pi}\)
Solution: Let us take a few variables: \(r_1=\) radius of circle A, \(r_2=\) radius of circle B, \(a=\) side of square WXYZ
Attachment:
WXYZ.png [ 8.57 KiB | Viewed 1173 times ]
Area of circle inscribed inside square WXYZ \(= \pi (\frac{a}{2})^2\)
We are asked the ratio of area of a circle inscribed within WXYZ to that of the area of circle A i.e., the value of \(\frac{\pi (\frac{a}{2})^2}{\pi (r_1)^2}=\frac{a^2}{4(r_1)^2}\)
This means we need the relation between \(a^2\) and \((r_1)^2\) to get our answer
According to the question, circle A has 3 times the area of circle B which means \(\pi (r_1)^2=3\pi (r_2)^2\) OR \((r_2)^2=\frac{(r_1)^2}{3}\)
Secondly, we are given circle B has one-sixth of the area of square WXYZ which means \(\pi (r_2)^2=\frac{1}{6}a^2\)
\(⇒\pi \frac{(r_1)^2}{3}=\frac{1}{6}a^2\)
\(⇒\frac{a^2}{(r_1)^2}=2\pi\)
We need the value of \(\frac{a^2}{4(r_1)^2}=\frac{2\pi}{4}=\frac{\pi}{2}\)
Hence the right answer is
Option C