10th Class Mathematics Triangles Question Bank MCQs - Triangles

  • question_answer
    The area of two similar triangles are \[\text{25 c}{{\text{m}}^{\text{2}}}\] and\[\text{121 c}{{\text{m}}^{\text{2}}}\].
    The ratio of their sides is:                                                                                                 (CBSE 2019)

    A) \[\text{25}:\text{121}\]

    B) \[\text{5}:\text{11}\]

    C) \[121:25\]

    D) \[11:5\]

    Correct Answer: B

    Solution :

        
    [b] By using the areas of similar triangles theorem,
    \[\frac{ar(\Delta ABC)}{ar(\Delta PQR)}={{\left( \frac{AB}{PQ} \right)}^{2}}={{\left( \frac{BC}{QR} \right)}^{2}}={{\left( \frac{AC}{PR} \right)}^{2}}\]
    \[\Rightarrow \,\,\,\,\,\,\frac{25}{121}={{\left( \frac{AB}{PQ} \right)}^{2}}={{\left( \frac{BC}{QR} \right)}^{2}}={{\left( \frac{AC}{PR} \right)}^{2}}\]
    \[\Rightarrow \,\,\,\,\,\,\frac{AB}{PQ}=\frac{BC}{QR}=\frac{AC}{PR}=\frac{5}{11}\] 


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