10th Class Mathematics Triangles Question Bank MCQs - Triangles

  • question_answer
    In the figure, find x in terms of a, b and c.

    A) \[\frac{ab}{a+c}\]

    B) \[\frac{ac}{b+c}\]

    C) \[\frac{bc}{a+b}\]

    D) \[\frac{ac}{a+b}\]

    Correct Answer: B

    Solution :

    [b] In \[\Delta KNP\] and \[\Delta KML\]
    \[\angle KNP=\angle KML=35{}^\circ \]           (Given)
    \[\angle K=\angle K\]              (Common)
    \[\therefore \,\,\,\,\,\,\,\,\Delta KNP\tilde{\ }\Delta KML\]
    (By AA similarity criterion)
                \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\frac{PN}{LM}=\frac{KN}{KM}\]
    (Corresponding sides of similar triangles are proportional)
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\frac{x}{a}=\frac{c}{KN+NM}=\frac{c}{c+b}\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,x=\frac{ac}{b+c}\]


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