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Find the area enclosed between two concentric circles, if their radii are 6 cm and 13 cm respectively.

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#### Solution

Area between two concentric circles = Area of larger cirde - area of smaller circle

Area of the drde = πr^{2}

Radius of bigger drde = r 1 = 13 cm

Radius of smaller drde = r 2 = 6 cm

Required area = `pi "r"1^2 - pi "r"2^2`

`= (22/7 xx 13 xx 13) - (22/7 xx 6 xx 6)`

= 531.1429 - 113.1429

= 418 cm^{2}

Hence, required area = 418 cm^{2}

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