1 Answer

Carl Von Blixen · Answer 1 · 2022-05-09T10:38:32+0000

▪︎Side 15 cm, 18 cm and x cm form a right angle triangle.

We know that :

$=\tt {hypotenuse}^(2) = {leg}^(2) + {leg}^(2)$

Which means :

$=\tt {15}^(2) + {x}^(2) = {18}^(2)$

$=\tt 225 + {x}^(2) = 324$

$=\tt {x}^(2) = 324 - 225$

$= \tt {x}^(2) = 99$

$\color{plum} =\tt x = 9.9 \: cm$

Thus, x (radius) = 9.9 cm

We know that :

$\color{hotpink}\tt \: Surface \: area \: of \: cone \color{plum}=\pi r(r + \sqrt{ {h}^(2) + {r}^(2) }$

Then, the surface area of this cone :

$= \tt3.14 * 9.9 *( 9.9 + \sqrt{ {15}^(2) + {9.9}^(2) } )$

$=\tt 3.14 * 9.9 *( 9.9 + √(323.01) )$

$=\tt 3.14 * 9.9 * (9.9 + 18)$

$=\tt 3.14 * 9.9 * 27.9$

$= \tt31.09 * 27.9$

$\color{plum} =\tt\bold{ 867.4 \: cm}$

Therefore, the surface area of this cone = 867.4 cm

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