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The total surface area of a cone whos...

The total surface area of a cone whose radius is `(r)/(2)` and slant height 2l is

A

`2 pir(l +r)`

B

`pir(l+(r)/(4))`

C

`pir(l+r)`

D

`2pirl`

Text Solution

Verified by Experts

The correct Answer is:
B
Given, radius `R= (r)/(2)` and slant height, L = 2l
`therefore` Total surface area of a cone `= piR( L +R) = pi xx (r)/(2)(2l +(r)/(2)) = pir (l +(r)/(4))`
Hence, the total surface area of a cone is `pir (l + (r)/(4))`
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