Ex 12.1, 1
The radii of two circles are 19 cm and 9 cm respectively. Find the radius of the circle which has circumference equal to the sum of the circumferences of the two circles.
Given that,
Radius of 1st circle = r1 = 9 cm
Radius of 2nd circle = r2 = 19 cm
Let the radius of required circle = r cm
According to question,
Circumference of required circle = Sum of circumference of two circles
Now,
Circumference of required circle = Sum of circumference of two circles
2πr = 18π+38π
2πr = 56 π
r = 56π/2π
r = 28
Hence, radius of new circle = r = 28 cm

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.

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