RS Aggarwal - Mathematics

Book: RS Aggarwal - Mathematics

Chapter: 18. Area of Circle, Sector and Segment

Subject: Maths - Class 10th

Q. No. 15 of Exercise 18A

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The circumferences of two circles are in the ratio 2:3. What is the ratio between their areas?


Ratio of circumferences of two circles = 2:3

Let the two circles be C1 and C2 with radii ‘r1’ and ‘r2’.

Circumference of circle = 2πr

Circumference of C1 = 2πr1

and Circumference of C2 = 2πr2



Squaring both sides, we get


Multiplying both sides by ‘’, we get


Area of circle = πr2


Hence, the ratio between the areas of C1 and C2 is 4:9.

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