Question

Diameters of three concentric circles are in the ratio 1:2:3.The sum of the circumference of these circles is 264cm.Find the are enclosed between second and third circles

Answer 1

let the common factor be x

so d are x,2x,3x

22/7 *x + 22/7 *2x +22/7*2x=264

22/7(2x +x+3x)=264

6x=12*7

x=14

d1 is 14

d2 is 28

d3 is 42

ar across 2nd circle

1. 22/7*14*14=616

ar across 3rd circle

22/7 *28*28 =2464

hope this would help you

Answer 2

Answer:

770cm²

Explanation:

given ratio of diameters is 1:2:3

let x,2x,3x be the diameters

sum of circumference of circles =264cm

radius is equal to x/2;2x/2,3x/2

radius=x/2,x,3x/2

r1=x/2

r2=x

r3=3x/2

2pie r1+2 pie r2+2 pie r3=264cm

2 pie(r1+r2+r3)=264

x/2+x+3x/2=(264×7)/(22×2)

3x=1848/44

3x=42

x=42/3

x=14

area enclosed between second and third circles is:-

pie r²of third circle -pie r²of second circle

area of third circle =pie r²

=(22/7)×(21)²

=1386cm²

area of second circle = pie r²

=(22/7)×(14)²

= 616cm²

area enclosed =1386cm²-616cm²

=770 cm²