Question

if the radius of a cone is 7cm and height is 10cm its total surface area will be ​

Answer 1

HeYa❤️...

Given:

radius(r) = 7cm

height(h) = 10cm

Solution:

$l {}^{2} = r {}^{2} + h {}^{2} \\ l = \sqrt{(7) {}^{2} + (10) {}^{2} } \\ l = \sqrt{49 + 100} \\ l = \sqrt{149}$

$total \: surface \: area \: of \: cone = \pi \: r(r + l) \\ \\ = \frac{22}{7} \times 7(7 + \sqrt{149} ) \\ \\ = \frac{22}{7} \times 49 + 7 \sqrt{149} \\ \\ = 22 \times 7 + 7 \sqrt{149} \\ \\ = 154 + 7 \sqrt{149} \\ \\ = 161 \sqrt{149} \\ \\ = 1965.255 \: cm {}^{2}$

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