Manipal Engineering Manipal Engineering Solved Paper-2015

  • question_answer
    In \[C{{l}^{-}}\] if \[{{l}^{-}}\]Then, c is the root of the equation

    A) \[B{{r}^{-}}\]     

    B) \[HOCl\]

    C) \[HCl{{O}_{2}}\]               

    D) \[HCl{{O}_{3}}\]

    Correct Answer: A

    Solution :

    We have, a = 4, b = 3 and \[\angle A={{60}^{o}}\] \[\because \]\[\cos A=\frac{{{b}^{2}}+{{c}^{2}}-{{a}^{2}}}{2bc}\] \[\therefore \]\[\cos {{60}^{o}}=\frac{9+{{c}^{2}}-16}{6c}\] \[\Rightarrow \]\[\frac{1}{2}\times 6c={{c}^{2}}-7\]\[\Rightarrow \]\[{{c}^{2}}-3c-7=0\]


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