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Mathematics

Find the radius and area of a circle if its circumference is 18π cm.

Mensuration

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Answer

Let radius = r cm.

By formula,

Circumference = 2πr

⇒ 2πr = 18π

⇒ 2r = 18

⇒ r = 9 cm.

Area of circle = πr2

= 227×92=22×817\dfrac{22}{7} \times 9^2 = \dfrac{22 \times 81}{7}

= 17827=25447\dfrac{1782}{7} = 254\dfrac{4}{7} cm2.

Hence, radius = 9 cm and area = 25447254\dfrac{4}{7} cm2.

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