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Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-30

  • question_answer
    \[{{(\cos \theta -\sin \theta )}^{2}}+{{(\cos \theta +\sin \theta )}^{2}}\] is equal to

    A)  0                    

    B)  1

    C)  2

    D) \[4\sin \theta \cos \theta \]

    Correct Answer: C

    Solution :

    Using \[{{(a-b)}^{2}}+{{(a+b)}^{2}}\] \[=2({{a}^{2}}+{{b}^{2}}),\] we have \[{{(\cos \theta -\sin \theta )}^{2}}+{{(\cos \theta +\sin \theta )}^{2}}\] \[=2({{\cos }^{2}}\theta +{{\sin }^{2}}\theta )=2\times 1=2\]             


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