8th Class Mathematics Mensuration Question Bank Mensuration

  • question_answer
    The sides of a triangle are \[11\text{ }cm,\text{ }15\text{ }cm\]and\[16\text{ }cm\]. What is the measure of the altitude to the largest side?

    A)  \[30\sqrt{7}\,cm\]                         

    B)  \[30\,cm\]         

    C)  \[\frac{15\sqrt{7}}{4}\,cm\]      

    D)         \[\frac{15\sqrt{7}}{2}\,cm\]

    Correct Answer: C

    Solution :

    By Heron's formula, we have area of triangle \[=\sqrt{s\,(s-a)\,(s-b)(s-c)}\] Here,                 \[s=\frac{11+15+16}{2}=\frac{42}{2}=21\,cm\] \[\therefore \] Area \[=\sqrt{21(10)\,(6)\,(5)}\]                 \[=30\sqrt{7}sq.\,cm\] \[\therefore \] Height  \[=\frac{2\,\,area}{base}=\frac{2\times 30\sqrt{7}}{16}\]                 \[=\frac{15\sqrt{7}}{4}\,cm\]


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