Question

A base radius of right circular cone 14 cm and height is 105 cm then find the curved surface of cone...
a)77cm²
b)770cm²
c)70cm²
d) none of these

please find step by step.........​

Answer 1

CORRECT QUESTION :

A base radius of right circular cone 14 cm and height is 10.5 cm then find the curved surface of cone...

a)77cm²

b)770cm²

c)70cm²

d) none of these

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

$\green{\therefore{\text{C.S.A\:of\:cone=770\:cm}^{2}}}$

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

$\green{ \underline \bold{Given : }} \\ : \implies \text{Radius(r) = 14 \: cm} \\ \\ : \implies \text{Height(h) = 10.5 \: cm} \\ \\ \red{ \underline \bold{To \: Find : }} \\ : \implies \text{C.S.A\: of \: cone = ?}$

• According to given question :

$\bold{As \: we \: know \: that} \\ : \implies \text{Slant \: height = hypotenuse \: of \: right \: circular \: cone} \\ \\ : \implies {h}^{2} = {p}^{2} + {b}^{2} \\ \\ :\implies {l}^{2} = {10.5}^{2} + {14}^{2} \\ \\ : \implies {l}^{2} = 110.25 + 196 \\ \\ : \implies {l} = \sqrt{306.25} \\ \\ \green{: \implies {l} = 17.5 \: cm} \\ \\ \bold{As \: we \: know \: that \: C.S.A \: of \: cone}\\ : \implies \text{C.S.A\: of \: cone} = \pi rl \\ \\ : \implies \text{C.S.A \: of \: cone} = \frac{22}{7} \times 14 \times 17.5 \\ \\ : \implies \text{C.S.A \: of \: cone} =22 \times 2 \times 17.5 \\ \\ \green{ : \implies \text{C.S.A\: of \: cone} =770 \: {cm}^{2}}$

Answer 2

Correct answer is (b)

$770cm {}^{2}$