Question

The radii of two circle are 13 cm and 6cm, respectively. Find the radius of the circle which has circumference of the two circles.

Answer 1

Let r cm be the radius of the required circleAccording to the question, we haveCircumference of the required circle having radius r cm. = Circumference of the circle having radius 13 cm + Circumference of the circle having radius 6 cm

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$2\pi \:r \: = 2\pi \: (13) + 2\pi \: r(6)$

[•circumference of circle = 2πr]

$= > 2\pi \: r \: = 2\pi(13 + 6) \\ = > r = 19cm$

[dividing both sides by 2π]

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Hence, the radius of the required circle is 19cm