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Find the diameter of a circle whose circumference is equal to the sum of circumference of circles with radius 10 cm, 12 cm, and 18 cm.

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#### Solution

Let the radius of the circle = R cm

∴ 2πR = 2π × 10 + 2π × 12 + 2π × 18

On dividing each term by 2π, we get:

R = 10 + 12 + 18 = 40 cm

∴ Radius of the circle obtained = 40 cm

And, its diameter = 2 × Radius

= 2 × 40 cm = 80 cm

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