SSC Sample Paper Mock Test-19 SSC CGL Tear-II Paper-1

  • question_answer
    The two opposite vertices of a square are \[(-1,2)\] \[(3,2).\]Find the coordinates of the other two vertices.

    A) (0, 1) and (3, 4)

    B)  (1, 0) and (1, 4)

    C)  (3, 5) and (2, 1)

    D)  (3, 4) and (1, 2)

    Correct Answer: B

    Solution :

    Let PQRM be a square and let P\[(-1,2)\]and R\[(3,2)\]be the vertices. Let the coordinates of Q be (x, y).
    \[\because \]       \[PQ=MR\]
    \[\Rightarrow \]   \[P{{Q}^{2}}=M{{R}^{2}}\]
    \[\Rightarrow \]\[{{(x+1)}^{2}}+{{(y-2)}^{2}}={{(x-3)}^{2}}+{{(y-2)}^{2}}\][\[\because \]Distance\[=\sqrt{{{({{x}_{2}}-{{x}_{1}})}^{2}}+{{({{y}_{2}}-{{y}_{1}})}^{2}}}\]]
    \[\Rightarrow \]\[{{x}^{2}}+1+2x+{{y}^{2}}+4-4y={{x}^{2}}+9-6x+{{y}^{2}}4-4y\]
    \[\Rightarrow \]   \[2x+1=-6x+9\]
    \[\Rightarrow \]   \[8x=8\]
    \[\Rightarrow \]   \[x=1\]                          ?(i)
    In \[\Delta PQR,\]we have\[P{{Q}^{2}}+Q{{R}^{2}}=P{{R}^{2}}\]
    \[{{(x+1)}^{2}}+{{(y-2)}^{2}}+{{(x-3)}^{2}}+{{(y-2)}^{2}}={{(3+1)}^{2}}+{{(2-2)}^{2}}\]\[\Rightarrow \]\[{{x}^{2}}+1+2x+{{y}^{2}}+4-4y+{{x}^{2}}+9-6x+{{y}^{2}}\]
    \[+4-4y={{4}^{2}}+{{0}^{2}}\]
    \[\Rightarrow \]\[2{{x}^{2}}+2{{y}^{2}}+2x-4y-6x-4y+1+4+9+4=16\]
    \[\Rightarrow \]   \[2{{x}^{2}}+2{{y}^{2}}-4x-8y+2=0\]
    \[\Rightarrow \]   \[{{x}^{2}}+{{y}^{2}}-2x-4y+1=0\]             ?(ii)
    Putting x = 1 from Eq. (i) in Eq. (ii), we get
    \[1+{{y}^{2}}-2-4y+1=0\]\[\Rightarrow \]\[{{y}^{2}}-4y=0\]
    \[\Rightarrow \]   \[y\,\,(y-4)=0\]\[\Rightarrow \]\[y=0\]or 4
    Hence, the required vertices of square are (1, 0) and (1, 4).


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