Question

the area of two circles are in the ratio 9: 16 find the ratio of their circumference

Answer 1

Let A1 = 9 and A2 = 16

Area of A1 / Area of A2 = 9 / 16

pi*r1^2 / pi*r2^2 = 9/16

r1 / r2 = 3 / 4

Now circumference is given by 2*pi*r

C1 : C2

= 2*pi*r1 : 2*pi*r2

= 2*pi*3 : 2*pi*4

= 3 : 4

Ratio of circumference is 3 : 4.


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Answer 2

Step-by-step explanation:

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The ratio between the areas of two circles is 16 : 9.

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asked Jun 14, 2019 in Class VII Maths by aditya23 (-2,153 points)

The ratio between the areas of two circles is 16 : 9. Find the ratio between their :

(i) radii

(ii) diameters

(iii) circumference

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1 Answer

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answered Jun 14, 2019 by muskan15 (-3,445 points)

(i) Let the radius of first circle = r1

And radius of second circle = r2

Given that ratio of the areas of circles

= 16 : 9



⇒ r1/r2 = 4/3

(ii) Let the diameter of first circle = d1

and diameter of second circle = d2

since, we know that diameter = 2 × radius

d1 = 2 × r1 = 2 × 4x = 8x

and d2 = 2 × r2 = 2 × 3x = 6x

Now, the ratios between the diameter of two circles = d1 :  d2

= 8x : 6x = 4 : 3

(iii) Now, consider the ratio of circumference of the circles

= 2πr1/2πr2 = r1/r2 = 4/3

∴ The ratio between the circumference of two circles = 4 :  3