CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2002

  • question_answer
    The general solution of the equation \[\sin \theta +\cos \theta =1\]is:

    A) \[\theta =2n\pi +\frac{\pi }{2},n=0,\pm 1,\,\pm 2\]

    B)  \[\theta -n\pi +\{{{(-1)}^{n}}+1\}\pi /4,n=0,\pm \,1,\pm \,2\]

    C)  \[\theta =n\pi +\{{{(-1)}^{n}}-1\}\frac{\pi }{4},n=0,\pm \,1,\,\pm 2\]

    D)  \[\theta =2n\pi ,n=0,\pm 1,\,\pm 2+...\]

    Correct Answer: C

    Solution :

    \[\sin \theta +\cos \theta =1\] \[\Rightarrow \]               \[\sin \theta \frac{1}{\sqrt{2}}+\cos \theta \frac{1}{\sqrt{2}}=\frac{1}{\sqrt{2}}\] \[\sin \left( \theta +\frac{\pi }{4} \right)=\sin \frac{\pi }{4}\] \[\Rightarrow \]               \[\theta +\frac{\pi }{4}=n\pi +{{(-1)}^{n}}\frac{\pi }{4}\] \[\theta =n\,\pi +{{(-1)}^{n}}\frac{\pi }{4}-\frac{\pi }{4},\] \[\theta =n\pi +\{{{(-1)}^{n}}-1\}\frac{\pi }{4}\]


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