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Question
The radius of the base of a cone is 5 cm and its height is 12 cm. Its curved surface area is
Options
60π cm2
65π cm2
30π cm2
None of these
Solution
65π cm2
Given: r = 5 cm, h = 12 cm
Slant height of the cone,` l = sqrt("r"^2 + "h"^2)`
`= sqrt((5)^2 + (12)^2)`
`= sqrt(25 + 144)`
`= sqrt(169)`
= 13 cm
Hence, the curved surface area of the cone` =pi"rl" `
`= (pixx5xx13) "cm"^2`
= 65 π cm2
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