the area of a circle is 38.5 sq.m. find its circumference (in cm)
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Solution :
Let the radius of the circle = r cm
i ) Area of the circle ( A ) = 38.5 cm²
=> πr² = 38.5
=> ( 22/7 )r² = 38.5
=> r² = ( 38.5 × 7 )/22
=> r² = ( 385 × 7 )/( 10 × 22 )
=> r² = ( 7/2 )²
=> r = 7/2 cm
ii ) Circumference ( C ) = 2πr
=> C = 2 × ( 22/7 ) × (7/2 )
= 22 cm
Therefore,
Circumference of the circle = 22 cm
••••
Let the radius of the circle = r cm
i ) Area of the circle ( A ) = 38.5 cm²
=> πr² = 38.5
=> ( 22/7 )r² = 38.5
=> r² = ( 38.5 × 7 )/22
=> r² = ( 385 × 7 )/( 10 × 22 )
=> r² = ( 7/2 )²
=> r = 7/2 cm
ii ) Circumference ( C ) = 2πr
=> C = 2 × ( 22/7 ) × (7/2 )
= 22 cm
Therefore,
Circumference of the circle = 22 cm
••••
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