Question

If the ratio of circumferences of two circles is 4:9 , what is the

ratio of their areas ?

a) 9:4 b) 16:81 c) 4:9 d) 2:3

full solve karke dikhana h ​

Answer 1

The solution is given in the picture....and your answer is

Option (b) 16:81

hope this help you..plz...mark it as brainlist..✌✌✌

Answer 2

Explanation:

Here let the radius of first circle be r1

And the radius of second circle be r2

So circumference of first circle/circumference of second circle =4/9

$\frac{2\pi \: r1}{2\pi \: r2} = \frac{4}{9}$

$cancelling \: both \: 2 \: and \: \pi$

$\frac{r1}{r2} = \frac{4}{9}$

Now calculating ratio of their areas

Area of first circle /area of second circle=

$\frac{2\pi(r1) {}^{2} }{2\pi(r2) {}^{2} }$

$cancelling \: 2 \: and \: \pi$

$( \frac{r1}{r2}) {}^{2} \: \: \: \: \: \: we \: can \: also \: write \: it \: like \: this$

$put \: value \: of \: \frac{r1}{r2} = \frac{4}{9}$

$( \frac{4}{9} ) {}^{2}$

$\frac{16}{81}$

Hence correct option is (b)