Question

The ratio between the radii of two circles is 5:7 ; find theratio between their circumference and area

Answer 1

$<b><font face=Copper black size=4 colour=purple>$$<b><marquee direction = "up" > <h3>$Let,

Radius of one circle = $\mathsf{r_1}$

Radius of another circle = $\mathsf{r_2}$

Now,

Given ratio :

$\mathsf{{r_1} \ / \ {r_2}}$ = 5 / 7

Now,

Circumference of one circle = 2π$\mathsf{r_1}$

Circumference of another circle = 2π$\mathsf{r_2}$

Their ratio -

= 2π$\mathsf{r_1}$ / 2π$\mathsf{r_2}$

= $\mathsf{{r_1} \ / \ {r_2}}$

= 5 / 7

= 5 : 7

Now,

Area of one circle = π$\mathsf{r^2_1}$

Area of another circle = π$\mathsf{r^2_2}$

Their ratio :

= π$\mathsf{r^2_1}$ / π$\mathsf{r^2_2}$

= $\mathsf{{r^2_1} \ / \ {r^2_2}}$

= ( 5 / 7 )²

= 25 / 49

= 25 : 49

^^"