7th Class Mathematics Mensuration Question Bank Mensuration

  • question_answer
    The sides of a triangle are 11 cm, 15 cm and 16cm. The altitude to 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 :

        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\[=\frac{30}{8}\sqrt{7}=\frac{15\sqrt{7}}{4}cm.\]   


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