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

  • question_answer
    In the figure, PQ is parallel to ST. AB is a straight line. Find\[\angle BST\].                

    A)  \[{{110}^{o}}\]                  

    B)  \[{{125}^{o}}\]      

    C)         \[{{152}^{o}}\]      

    D)         \[{{98}^{o}}\]        

    Correct Answer: A

    Solution :

    Since, \[PQ||ST\] \[\therefore \]\[\angle PQS=\angle QST\]    (Alternate angles) \[\Rightarrow \]  \[\angle QST={{98}^{o}}\] \[\Rightarrow \] \[\angle QSA+\angle AST={{98}^{o}}\] \[\Rightarrow \]  \[\angle AST={{98}^{o}}-{{28}^{o}}={{70}^{o}}\] Now, AB is a straight line. \[\therefore \] \[~\angle AST+~\angle TSB={{180}^{o}}\] (linear pair) \[\Rightarrow \] \[\angle TSB={{180}^{o}}-{{70}^{o}}={{110}^{o}}\]


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