JEE Main & Advanced Mathematics Functions Question Bank Limits

  • question_answer
    \[\underset{\alpha \to \beta }{\mathop{\lim }}\,\left[ \frac{{{\sin }^{2}}\alpha -{{\sin }^{2}}\beta }{{{\alpha }^{2}}-{{\beta }^{2}}} \right]=\] [MP PET 2001]

    A)                 0

    B)                 1

    C)                 \[\frac{\sin \beta }{\beta }\]

    D)                 \[\frac{\sin 2\beta }{2\beta }\]

    Correct Answer: D

    Solution :

                       \[\underset{\alpha \to \beta }{\mathop{\lim }}\,\frac{{{\sin }^{2}}\alpha -{{\sin }^{2}}\beta }{{{\alpha }^{2}}-{{\beta }^{2}}}\]                    Applying L-Hospital?s rule,                 \[\underset{\alpha \to \beta }{\mathop{\text{lim}}}\,\frac{2\sin \,\alpha \,\,\cos \alpha }{2\alpha }=\underset{\alpha \to \beta }{\mathop{\text{lim}}}\,\frac{\sin \,\,2\alpha }{2\alpha }=\frac{\sin \,\,2\beta }{2\beta }\].


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