Question

if the ratio of radii of two radii of two circle is 2:5 the ratio of their circumference is

a) 5:2
b) 4:5
c) 3:5
d) 2:5​

Answer 1

Answer:

2:5 30The ratio of the radii of two circles is 2:5.

Let first circle's radius be '2x'

and second circle be '5x'

First circle circumference

Circumference =2πr

= 2 × 22/7 × 2x

= 44/7 × 2x

= (88x)/7

Second circle circumference

Circumference = 2πr

= 2 × 22/7 × 5x= 44/7 × 5x

= (220x)/7

Ratio of two circles circumference =

= \bf \frac{(\frac{88x}{7})}{(\frac{220x}{7})}

( 7x220x )

( 7 x88x )

= \bf \frac{88x}{7}\times\frac{7}{220x} 7

88x × 220x7= 2:5

Hence,so the ratio of the circumference of two circles=2:5