JEE Main & Advanced JEE Main Paper (Held On 25 April 2013)

  • question_answer
                    Let \[\operatorname{A}=\{\theta :\sin (\theta )=\tan (\theta )\}\] and \[B=\{\theta :\cos (\theta )=1\}\] be two sets. Then:     JEE Main Online Paper ( Held On 25  April 2013 )

    A)                 \[\operatorname{A}=B\]                            

    B)                                        \[\operatorname{A}\not\subset B\]

    C)                                        \[\operatorname{B}\not\subset \operatorname{A}\]                  

    D)                                        \[A\subset B\]and\[B-A\ne \phi \]

    Correct Answer: B

    Solution :

                    Let \[A=\{\theta :\sin \theta =\tan \theta \}\]and\[B=\{\theta :\cos \theta =1\}\] Now,\[\left\{ \theta :\sin \theta =\frac{\sin \theta }{\cos \theta } \right\}\] \[=\{\theta :\sin \theta (\cos \theta -1)=0\}\] \[=\{\theta =0,\pi ,2\pi ,3\pi ,.....\}\] For\[B:\cos =\theta =1\Rightarrow \theta =\pi ,2\pi ,4\pi ,......\] This shows that A is not contained in B. i.e. \[A\not\subset B.\]but\[B\subset A.\]


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