Question

An open cone has a slant height of 5m and a curved surface area of 251 m². Find the radius of the circular base.​

Answer 1

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c.s.a = 251 m.sq.

l = 5m.

r = ❔

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curved surface area of cone = π × r × l

Atq,

3.14 × r × 5 = 251

r = 251 / 3.14 × 5

r = 251 / 15.7

r = 2510 / 157

radius = $\dfrac\pink{2510}{157}$ Ans

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Answer 2

Given :

• Slant Height of Cone = 5m.
• C.S.A of Cone = 251m².

To Find :

• Radius of Base of Cone.

Solution :

$\longmapsto\tt{Slant\:height(l)=5m}$

Using Formula :

$\longmapsto\tt\boxed{C.S.A\:of\:Cone=\pi{rl}}$

Putting Values :

$\longmapsto\tt{251=\dfrac{22}{7}\times{r}\times{5}}$

$\longmapsto\tt{251\times{7}=110r}$

$\longmapsto\tt{1757=110r}$

$\longmapsto\tt{r=\cancel\dfrac{1757}{110}}$

$\longmapsto\tt\bf{r=15.9m}$

So , The Radius of the Cone is 15.9 m..

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• C.S.A of Cone = πrl
• T.S.A of Cone = πrl(l+r)
• Volume of Cone = 1/3 πr²h
• Slant Height of Cone = √(r)²+(h)²

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