Question

the volume of a cylindrical rod is 620 cm cube,its height is 20 cm then find its radius...​

Answer 1

❏ Question:-

@ The volume of a cylindrical rod is 620 cm cube,its height is 20 cm then find its radius...

❏ Solution:-

✦Given:-

• volume of the cylindrical rod is=620 cm³.

• height(h) of the cylinder rod is= 20 cm.

✦To Find:-

• The base radius of the cylindrical rod=?

✦Explanation:-

Let, base radius of the cylinder kal rod is = r cm.

Now , using the Formula,

$\sf\longrightarrow Volume=\pi r{}^{2}h$

$\sf\longrightarrow 620=\frac{22}{7} \times r{}^{2}\times 20$

$\sf\longrightarrow \cancel{62}\cancel0\times\frac{7}{22}\times\frac{1}{\cancel2\cancel0}=r^2$

$\sf\longrightarrow\frac{31\times7}{22}=r^2$

$\sf\longrightarrow\sqrt{\frac{217}{22}}=r$

$\sf\longrightarrow\boxed{ \large{\red{r= 3.14 \:cm}}}$ (almost).

∴ Base radius of the cylindrical rod is =3.14 cm

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❏ Formula Used:-

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✦ CYLINDER✦

For a right circular cylinder of base radius r and height h,

$\sf\longrightarrow\boxed{ L.S.A=2\pi r h}$

$\sf\longrightarrow\boxed{ T.S.A.=2\pi r (r+h)}$

$\sf\longrightarrow \boxed{Volume=\pi r{}^{2}h}$

Where, •L.S.A.=Curved Surface area.

•T.S.A.=Total Surface Area.

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$\underline{ \huge\mathfrak{hope \: this \: helps \: you}}$

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Answer 2

$\huge\underline\mathrm{Question-}$

The volume of a cylindrical rod is 620 cm³, its height is 20 cm, then find its radius.

$\huge\underline\mathrm{Answer-}$

$\large{\boxed{\blue{\rm{Radius\:of\:cylindrical\:rod=3.14\:cm\:(approx)}}}}$

$\huge\underline\mathrm{Explanation-}$

$\begin{lgathered}\bold{Given} \begin{cases}\sf{Volume\:of\:cylinderical\:rod=620\:cm^3} \\ \sf{height\:of\:cylindrical\:rod=20\:cm}\end{cases}\end{lgathered}$

To find :

• Radius of cylindrical rod.

Solution :

We know that,

$\large{\boxed{\rm{\red{Volume\:of\:cylinder=\pi\:r^2\:h}}}}$

★ Now putting the given values,

$\longrightarrow$ 620 = $\dfrac{22}{7}$ × r² × (20)

$\longrightarrow$ r² = $\dfrac{\cancel{620}×7}{22×\cancel{20}}$

$\longrightarrow$ r² = $\dfrac{31×7}{22}$

$\longrightarrow$ r² = $\dfrac{217}{22}$

$\longrightarrow$ r² = 9.8636

$\longrightarrow$ r = $\sqrt{9.8636}$

$\large{\boxed{\blue{\rm{\therefore\:radius\:of\:cylindrical\:rod=3.14\:cm\:(approx)}}}}$