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प्रश्न
The radius of a circle is 5 m. Find the circumference of the circle whose area is 49 times the area of the given circle.
उत्तर
Area of the circle having radius 5 m is
A = π × (5)2
= 25 π m2
Let r be the radius of the circle whose area is 49 times of the given circle.
π r2 = 49 × (π x 52)
r2 = (7 × 5)2
r = 35 m
Hence circumference of the circle
circumference = 2πr
circumference = 2 × `22/7`× 35
circumference = 220 m
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