CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2004

  • question_answer
    The equation\[a\text{ }cos\theta +b\text{ }sin\theta =c\]has a solution, when a, b and c are real numbers such that:

    A)  \[a<b<c\]

    B)  \[a=b=c\]

    C) \[{{c}^{2}}\le {{a}^{2}}+{{b}^{2}}\]

    D)  \[{{c}^{2}}<{{a}^{2}}-{{b}^{2}}\]

    E)  for all real values of a, b and c

    Correct Answer: C

    Solution :

    The given equation is \[a\text{ }cos\theta +b\text{ }sin\theta =c\] Since, \[\sqrt{{{a}^{2}}-{{b}^{2}}}\le a\cos \theta +b\sin \theta \le \sqrt{{{a}^{2}}+{{b}^{2}}}\] \[\Rightarrow \]               \[{{c}^{2}}\le \sqrt{{{a}^{2}}+{{b}^{2}}}\]


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