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

  • question_answer
    Observe the figure given. Compute the sum of x, y and z.

    A)  \[{{180}^{o}}\]

    B)         \[{{70}^{o}}\]

    C)  \[{{190}^{o}}\]  

    D)         \[{{80}^{o}}\]

    Correct Answer: C

    Solution :

     From the figure, \[150-x+70-x+x={{180}^{o}}\] \[\Rightarrow \] \[x={{220}^{o}}-{{180}^{o}}={{40}^{o}}\] Since \[AE||BD,\] \[AE||BD,\] \[y=x\] as they are alternate angles. In \[\Delta BCD,\] \[\angle BDC=x\] (Alternate angles) \[70-x+x+z={{180}^{o}}\] \[\Rightarrow \] \[z={{110}^{o}}\] \[\therefore \]The required sum \[=x+y+z={{40}^{o}}+{{40}^{o}}+{{110}^{o}}={{190}^{o}}\]


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