CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    If A (0, 0), B (12, 0), C (12, 2), D (6, 7) and E (0, 5) are the vertices of the pentagon ABCDE, then its area in square units, is

    A)  58                                         

    B)  60

    C)  61                         

    D)         62

    E)  63

    Correct Answer: E

    Solution :

    Let          \[({{x}_{1}},{{y}_{1}})=(0,0)\] \[({{x}_{2}},{{y}_{2}})=(12,0)\]                 \[({{x}_{3}},{{y}_{3}})=(12,2)\]                 \[({{x}_{4}},{{y}_{4}})=(6,7)\]                 \[({{x}_{5}},{{y}_{5}})=(0,5)\] \[\therefore \]Area of pentagon \[=\frac{1}{2}\left[ \begin{matrix}    {{x}_{1}}{{y}_{2}}+{{x}_{2}}{{y}_{3}}+{{x}_{3}}{{y}_{4}}+{{x}_{4}}{{y}_{5}}  \\    +{{x}_{5}}{{y}_{1}}-({{y}_{1}}{{x}_{2}}+{{y}_{2}}{{x}_{3}}+{{y}_{3}}{{x}_{4}})  \\    +{{y}_{4}}{{x}_{5}}+{{y}_{5}}{{x}_{1}})  \\ \end{matrix} \right]\] \[=\frac{1}{2}\left[ \begin{align}   & 0(0)+12(2)+12(7)+6(5)+0(0) \\  & -\{0+0+2(6)+7(0)+5(0)\} \\ \end{align} \right]\] \[=\frac{1}{2}[(24+84+30-12)]=63\,sq\,unit\]


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