BCECE Engineering BCECE Engineering Solved Paper-2013

  • question_answer
    If \[\tan x.\tan y=a\]and \[x+y=\frac{\pi }{6},\]then tan \[x\]and \[\tan \,y\]satisfy the equation

    A)  \[{{x}^{2}}-\sqrt{3}(1-a)x+a=0\]

    B)  \[\sqrt{3}{{x}^{2}}-(1-a)x+a\sqrt{3}=0\]

    C)  \[{{x}^{2}}+\sqrt{3}(1+a)x-a=0\]

    D)  \[\sqrt{3}{{x}^{2}}+(1+a)x-a\sqrt{3}=0\]

    Correct Answer: B

    Solution :

    \[\because \]  \[\tan x.\tan y=a\] and \[\tan (x+y)=\tan \left( \frac{\pi }{6} \right)\] \[\Rightarrow \]               \[\frac{\tan x+\tan y}{1-\tan x.\tan \,y}=\frac{1}{\sqrt{3}}\] \[\Rightarrow \]               \[\tan x+\tan y=\frac{1}{\sqrt{3}}(1-a)\] Equation whose roots are \[\tan x\]and \[\tan y\]is \[{{x}^{2}}-\frac{(1-a)}{\sqrt{3}}.x+a=0\]                 \[\Rightarrow \]               \[\sqrt{3}{{x}^{2}}-(1-a)x+a\sqrt{3}=0\]


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