9th Class Mathematics Heron's Formula Question Bank Herons Formula

  • question_answer
    The sides of a triangle are 11 cm, 15 err, and 16 cm. The altitude to the largest side is____.

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

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

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

    D)         \[30\,cm\]                    

    Correct Answer: C

    Solution :

    We have, sides of triangle 11 cm, 15 cm and 16 cm. \[s=\frac{11+15+16}{2}=21\] \[\therefore \]Area of triangle \[=\sqrt{21(21-11)(21-15)(21-16)}\] \[=30\sqrt{7}\,c{{m}^{2}}\] Let altitude to the largest side be h cm \[\therefore \]      \[\frac{1}{2}\times 16\times h=30\sqrt{7}\Rightarrow 8h=30\sqrt{7}\] \[\Rightarrow \]   \[h=\frac{15\sqrt{7}}{4}\,cm\]


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