Question

the ratio of radius of two circles is 3:4 then what is ratio of their areas?​

Answer 1

Given:

Ratio of radius of two circles = 3:4

To find:

Ratio of their areas = ?

Solution:

Let the radius be = r1 and r2

Let their areas be = a1 and a2

$\:area \: ofcircle \: = \: \pi {r}^{2}$

$= > \: \frac{r1}{r2} = \: \frac{a1}{a2}$

$= > \: \frac{3}{4} = \: \frac{(\pi {r1)}^{2} }{(\pi {r2)}^{2} }$

$= > \: \frac{3}{4} = \: \frac{{(r1)}^{2} }{ {(r2)}^{2} }$

$= > \: \frac{ {3}^{2} }{ {4}^{2} } = \: \frac{r1}{r2}$

$= > \: \frac{9}{16} = \: \frac{r1}{r2}$

Hence, the ratio of their areas is 9:16

hope it helped you...