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

  • question_answer
    In the given figure (not drawn to scale), AD is parallel to BC. JDK, GHCI, EABF are straight and parallel lines. Find:
    (i) \[\angle GHD-\angle HDC\]
    (ii) \[\angle BCl+\angle HAB\].
               

    A)
    (i) (ii)
    \[{{58}^{o}}\]      \[{{150}^{o}}\]
                   

    B)
    (i) (ii)
    \[{{48}^{o}}\]      \[{{150}^{o}}\]
                   

    C)
    (i) (ii)
    \[{{58}^{o}}\]      \[{{180}^{o}}\]
                   

    D)
    (i) (ii)
    \[{{48}^{o}}\]     \[{{180}^{o}}\]
               

    Correct Answer: D

    Solution :

    (i) \[JK||Gl\]and DH is transversal. \[\therefore \]  \[\angle GHD=\angle HDK\](Alternate angles) \[\Rightarrow \] \[\angle GHD=\angle HDC+{{48}^{o}}\] \[\Rightarrow \] \[\angle GHD-\angle HDC={{48}^{o}}\] (ii)  \[Gl||EF\]and BC is transversal. \[\angle BCl+\angle CBF={{180}^{o}}\] (Co-interior angles) \[\angle BCl+{{66}^{o}}={{180}^{o}}\] \[\angle BCl={{180}^{o}}-{{66}^{o}}={{114}^{o}}\] As, \[HA||CB,\]and AB is transversal \[\angle CBF=\angle HAB\] (Corresponding angles) \[\angle HAB={{66}^{o}}\] Now. \[\angle BCl+\angle HAB={{114}^{o}}+{{66}^{o}}={{180}^{o}}\]


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