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7th Class Mathematics Lines and Angles Question Bank Lines and Angles

  • question_answer
     In the figure, \[\overline{AB},\,\,\overline{CD}\] and \[\overline{EF}\] are three straight lines that interesect at O. If y is thrice x, find the value of y.

    A)                  \[{{97.5}^{o}}\]                 

    B)         \[{{35}^{o}}\]

    C)                  \[{{32.5}^{o}}\]               

    D)         \[{{98}^{o}}\]

    Correct Answer: A

    Solution :

     From the figure, \[\angle AOC={{50}^{o}}\] (Vertically opposite angles) Given y is thrice x, we have \[x+{{50}^{o}}+y={{180}^{o}}\] (Angle on a straight line) \[\Rightarrow \] \[x+{{50}^{o}}+3x={{180}^{o}}\] \[\Rightarrow \] \[x=\frac{{{130}^{o}}}{4}={{32.5}^{o}}\] \[\therefore \] \[y=3x=3(32.5)={{97.5}^{o}}\]


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