10th Class Mathematics Triangles Question Bank MCQs - Triangles

  • question_answer
     
    In \[\Delta PQR\], \[ST||QR\], \[\frac{PS}{SQ}=\frac{3}{5}\] and \[PR=28\,cm\], then the value of PT is

    A) 9.5cm

    B) 9cm

    C) 10cm

    D) 10.5cm

    Correct Answer: D

    Solution :

    Given, \[ST\,|\,\,|\,QR\], \[PS/SQ=3/5\] and \[PR=28\,cm\]
     By using basic proportionality theorem, we get
    \[\frac{PS}{SQ}=\frac{PT}{TR}\Rightarrow \,\,\frac{PS}{SQ}=\frac{PT}{PR-PT}\]
    \[\Rightarrow \,\,\,\frac{3}{5}=\frac{PT}{28-PT}\]
    \[\Rightarrow \,\,\,3\left( 28-PT \right)=5PT\]
    \[\Rightarrow \,\,\,84=5\,\,PT+3\,PT\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,PT=\frac{84}{8}\]
    \[\Rightarrow \,\,\,\,PT=10.5\,\,\,cm\]
    Hence, the length of PT is 10.5 cm.


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