J & K CET Engineering J and K - CET Engineering Solved Paper-2010

  • question_answer
    \[(1-\tan A)\,(\cot \,A+1)\] is equal to

    A)  \[(1-\tan A)\,(1+tanA)\]

    B)  \[(1+\tan A)\,(cot\,A-1)\]

    C)  \[(1+\tan A)\,(1-cot\,A)\]

    D)  \[(\tan \,A-1)\,(\cot \,A-1)\]

    Correct Answer: B

    Solution :

    \[(1-\tan A)\,(\cot \,A+1)\] \[=\left( 1-\frac{1}{\cot \,A} \right)\,\left( \frac{1}{\tan \,A}+1 \right)\] \[=\left( \frac{\cos \,A-1}{\cot \,A} \right)\,\left( \frac{1+\tan \,A}{\tan \,A} \right)\] \[=(1+\tan \,A)(\cot \,A-1)\]


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