10th Class Mathematics Triangles Question Bank Triangles

  • question_answer
    In \[\Delta ABC,\] \[AB=AC\] and D is a point on side AC, such that \[B{{C}^{2}}=AC\times CD\] then BD=

    A)  AB                             

    B)  \[AC\]

    C)  BC                 

    D)         None of these

    Correct Answer: C

    Solution :

    \[B{{C}^{2}}=AC\times DC\]                [Given] \[\Rightarrow \]            \[\frac{BC}{DC}=\frac{AC}{BC}\] Thus, in  \[\Delta ABC\]and \[\Delta BDC,\]we have \[\frac{BC}{DC}=\frac{AC}{BC}\] and \[\angle C=\angle C\] [Common] \[\therefore \]  \[\Delta ABC\tilde{\ }\Delta BDC\]       [By SAS similarity] \[\Rightarrow \]            \[\frac{AC}{BC}=\frac{AB}{BD}\] \[\Rightarrow \]            \[\frac{AC}{BC}=\frac{AB}{BD}\] [\[\because \] AB = AC (Given)] \[\Rightarrow \]            \[BD=BC\]


You need to login to perform this action.
You will be redirected in 3 sec spinner