Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-33

  • question_answer
    \[\frac{\sin A+\sin B}{\cos A-\cos B}+\frac{\cos A+\cos B}{\sin A-\sin B}\]is equal to

    A)  0        

    B)         sin A cos B

    C)  cos A cos B      

    D)  tan A tan B

    Correct Answer: A

    Solution :

    Given expression \[=\frac{({{\sin }^{2}}A-{{\sin }^{2}}B)+(co{{s}^{2}}A-{{\cos }^{2}}B)}{(\cos A-\cos \,\,B)(sin\,\,A-sin\,\,B)}\] \[=\frac{({{\sin }^{2}}A+{{\cos }^{2}}A)-({{\sin }^{2}}B+{{\cos }^{2}}B)}{(\cos A-\cos B)(\sin A-\sin B)}\] \[=\frac{(1-1)}{(\cos A-\cos B)(\sin A-\sin B)}=0\]


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