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Question
The total surface area of a cone whose radius is `r/2` and slant height 2l is ______.
Options
`2pir (l + r)`
`pir (l + r/4)`
`pir(l + r)`
`2pirl`
Solution
The total surface area of a cone whose radius is `r/2` and slant height 2l is `underlinebb(pir (l + r/4))`.
Explanation:
The formula of total surface area of cone = Area of the base + Curved surface area of cone
= `pi(r/2)^2 + pi(r/2) xx 2l`
= `(pir)/2 (r/2 + 2l)`
= `(pir)/2 (r + 4l)`
= `pir(l + r/4)`
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