Question

Q. The radius of two circles are 10 cm and 9 cm respectively. Find the radius of the circle which has circumference equal to the sum of the circumference of the two circles.
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Answer 1

Step-by-step explanation:

Let the radius of required circle =r cm

Radius of 1st circle r1 =10 cm

Radius of 2nd circle r2 =9cm

As per the question

Circumference of the required circle = Sum of circumference of two circles

Circumference of small circle =2πr

1

=2π×10

=20π

Circumference of small circle =2πr

2

=2π×9

=18π

Now,

Circumference of the required circle = Sum of circumference of two circles

2πr=20π+18π

2πr=38π

r= 38π/2π

r=19 cm