CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2007

  • question_answer
    If sec a and cosec a are the roots of the equation\[{{x}^{2}}-px+q=0,\]then

    A)  \[{{p}^{2}}=p+2q\]        

    B)  \[{{q}^{2}}=p+2q\]

    C)  \[{{p}^{2}}=q(p+2)\]

    D)         \[{{q}^{2}}=p(p+2)\]

    E)  \[{{p}^{2}}=q(q-2)\]

    Correct Answer: C

    Solution :

    \[\because \] \[sec\alpha \]and\[cosec\alpha \]are the roots of the equation\[{{x}^{2}}-px+q=0.\] \[\therefore \]\[sec\alpha +cosec\alpha =p\]and \[sec\alpha \,cosec\alpha =q\] \[\Rightarrow \] \[\frac{\sin \alpha +\cos \alpha }{\sin \alpha \cos \alpha }=p\]and \[\sin \alpha \cos \alpha =\frac{1}{q}\] \[\Rightarrow \]               \[{{(\sin \alpha +\cos \alpha )}^{2}}={{\left( \frac{p}{q} \right)}^{2}}\] \[\Rightarrow \] \[{{\sin }^{2}}\alpha +{{\cos }^{2}}\alpha +2\sin \alpha +\cos \alpha =\frac{{{p}^{2}}}{{{q}^{2}}}\] \[\Rightarrow \] \[{{q}^{2}}\left( 1+\frac{2}{q} \right)={{p}^{2}}\] \[\Rightarrow \]               \[q(q+2)={{p}^{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner