CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    The circumcentre of the triangle with vertices (0, 30), (4, 0) and (30, 0) is

    A)  (10, 10)               

    B)         (10, 12)

    C)  (12, 12)               

    D)         (15, 15)

    E)  (17, 17)

    Correct Answer: E

    Solution :

    Let the circumcentre of triangle be\[P(x,\text{ }y)\]and let the vertices of a triangle be A (0, 30), B (4, 0) and C (30, 0). \[\therefore \]  \[P{{A}^{2}}=P{{B}^{2}}=P{{C}^{2}}\] \[\Rightarrow \]\[{{(x-0)}^{2}}+{{(y-30)}^{2}}\]                                 \[={{(x-4)}^{2}}+{{(y-0)}^{2}}\]                                 \[={{(x-30)}^{2}}+{{(y-0)}^{2}}\] From Und and IIIrd terms, \[{{x}^{2}}+{{y}^{2}}-60y+900={{x}^{2}}+{{y}^{2}}-8x+16\] \[\Rightarrow \]               \[8x-60y+884=0\]                              ...(i) From IInd and IIIrd terms, \[{{x}^{2}}-8x+16+{{y}^{2}}={{x}^{2}}-60x+900+{{y}^{2}}\] \[\Rightarrow \]\[52x=884\Rightarrow x=17\] On putting x = 17 in Eq. (i), we get \[y=17\] Hence, required point is (17, 17).


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