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Probability

Question
CBSEENMA9003433

 Find the total surface area of a cone whose radius is and slant height is 2l.

Solution

Total surface area

equals space space space πRL plus πR squared
equals space space space straight pi open parentheses straight r over 2 close parentheses left parenthesis 2 straight l right parenthesis plus straight pi open parentheses straight r over 2 close parentheses squared
equals space space space πrl plus πr squared over 4
equals space πr over 4 left parenthesis 4 straight l plus straight r right parenthesis