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# The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has a circumference equal to the sum of the circumferences of the two circles.Q.1

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Find the best solution of ncert class 10 areas related to circles . How i solve the exercise 12.1 question number 1 please give me the easiest and best solution of this solution.The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has a circumference equal to the sum of the circumferences of the two circles.

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1. The radius of the 1stÂ circle = 19 cm (given)

âˆ´ Circumference of the 1stÂ circle = 2Ï€Ã—19 = 38Ï€ cm

The radius of the 2ndÂ circle = 9 cm (given)

âˆ´ Circumference of the 2ndÂ circle = 2Ï€Ã—9 = 18Ï€ cm

So,

The sum of the circumference of two circles = 38Ï€+18Ï€ = 56Ï€ cm

Now, let the radius of the 3rdÂ circle = R

âˆ´ The circumference of the 3rdÂ circle = 2Ï€R

It is given that sum of the circumference of two circles = circumference of the 3rdÂ circle

Hence, 56Ï€ = 2Ï€R

Or, R = 28 cm.

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