JEE Main & Advanced Mathematics Conic Sections Question Bank Hyperbola

  • question_answer
    If q is the acute angle of intersection at a real point of intersection of the circle \[{{x}^{2}}+{{y}^{2}}=5\] and the parabola \[{{y}^{2}}=4x\] then tanq is equal to                                                                    [Karnataka CET 2005]

    A)            1     

    B)            \[\sqrt{3}\]

    C)            3     

    D)            \[\frac{1}{\sqrt{3}}\]

    Correct Answer: C

    Solution :

                      Solving equations \[{{x}^{2}}+{{y}^{2}}=5\] and \[{{y}^{2}}=4x\]                    we get \[{{x}^{2}}+4x-5=0\] i.e., \[x=1,\,-5\]                    For \[x=1\]; \[{{y}^{2}}=4\] Þ \[y=\pm 2\]                    For \[x=-5\]; \[{{y}^{2}}=-20\](imaginary values)                    \ Points are (1, 2)(1, ?2); \[{{m}_{1}}\] for \[{{x}^{2}}+{{y}^{2}}=5\] at (1, 2)                    \[{{\left. \frac{dy}{dx}=-\frac{x}{y} \right|}_{(1,\,2)}}=-\frac{1}{2}\]Similarly, \[{{m}_{2}}\] for \[{{y}^{2}}=4x\] at (1,2) is 1.                    \\[\tan \theta =\left| \frac{{{m}_{1}}-{{m}_{2}}}{1+{{m}_{1}}{{m}_{2}}} \right|=\left| \frac{-\frac{1}{2}-1}{1-\frac{1}{2}} \right|=3\].


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