8th Class Mathematics Mensuration Question Bank Mensuration

  • question_answer Find the total surface area of a cone, it its slant height is 9 m and the radius of its base is 12 m.

    A)  562 \[{{m}^{2}}\]                  

    B)  792 \[{{m}^{2}}\]  

    C)  692 \[{{m}^{2}}\]                  

    D)  600 \[{{m}^{2}}\]

    Correct Answer: B

    Solution :

    (b): \[TSA=\pi rl+\pi {{r}^{2}}\] \[\pi r+\pi {{r}^{2}}\] \[=\frac{22}{7}\left[ 12\times 9+{{12}^{2}} \right]\] \[=\frac{22\times 12}{7}\times 21=22\times 12\times 3=792.\]


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