Question
If the radius of a sphere is increased by 2 cm, then its surface area increases by 352`cm^2`. the radius of the sphere before the increase was :
Answer: Option D
Was this answer helpful ?
`4 pi (r + 2)^2 - 4 pi r^2 = 352`
`hArr (r + 2)^2 - r^2 = (352 xx 7/22 xx 1/4)` = 28.
`hArr ( r + 2 + r) ( r + 2 - r) = 28`
`hArr 2 r + 2 = 14`
`hArr r = (14/2 - 1)` = 6 cm
Was this answer helpful ?
More Questions on This Topic :
Latest Videos
Latest Test Papers
Submit Solution