Question

The radius and vertical height of a cone are 5cm and 12cm . Find its C.S.A

Answer 1

$\blue{\bold{\underline{\underline{Answer:}}}}$

$\green{\therefore{\text{C.S.A\:of\:cone=204.1\:cm}^{2}}}$

$\orange{\bold{\underline{\underline{Step-by-step\:explanation:}}}}$

$\green{ \underline \bold{Given : }} \\ : \implies \text{Radius(r) = 5 \: cm} \\ \\ : \implies \text{Height(h) =12\: cm} \\ \\ \red{ \underline \bold{To \: Find : }} \\ : \implies \text{C.S.A\: of \: cone = ?}$

• According to given question :

$\bold{As \: we \: know \: that} \\ : \implies \text{Slant \: height = hypotenuse \: of \: right \: circular \: cone} \\ \\ : \implies {h}^{2} = {p}^{2} + {b}^{2} \\ \\ :\implies {l}^{2} = {12}^{2} + {5}^{2} \\ \\ : \implies {l}^{2} = 144+ 25 \\ \\ : \implies {l} = \sqrt{169} \\ \\ \green{: \implies {l} = 13\: cm} \\ \\ \bold{As \: we \: know \: that \: C.S.A \: of \: cone}\\ : \implies \text{C.S.A\: of \: cone} = \pi rl \\ \\ : \implies \text{C.S.A \: of \: cone} = \frac{22}{7} \times 5 \times 13 \\ \\ : \implies \text{C.S.A \: of \: cone} =3.14 \times 65\\ \\ \green{ : \implies \text{C.S.A\: of \: cone} =204.1\: {cm}}^{2}$