CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2004

  • question_answer
    The number of solutions of the equation \[tan\text{ }x+sec\text{ }x=2\text{ }cos\text{ }x\]and\[\cos x\ne 0\]lying in the interval\[(0,2\pi )\]is:

    A)  2                                            

    B)  1

    C)  0                            

    D)         3

    E)  4

    Correct Answer: A

    Solution :

    \[tan\text{ }x+sec\text{ }x=2\text{ }cos\text{ }x\] \[\Rightarrow \] \[1+sin\text{ }x=2-2\text{ }si{{n}^{2}}x\] \[\Rightarrow \] \[2\text{ }si{{n}^{2}}x+sin\text{ }x-1=0\] \[\Rightarrow \] \[2\text{ }si{{n}^{2}}x+2\text{ }sin\text{ }x-sin\text{ }x-1=0\] \[\Rightarrow \] \[(2\text{ }\sin x-1)(sin\text{ }x+1)=0\] \[\Rightarrow \] \[sin\text{ }x=-1,\frac{1}{2}.\] \[\therefore \]Number of solution in the interval \[(0,2\pi )=2\]


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