Question

The diameter of the base of a right circular cylinder in 4.2 dm and it's height is 1 dm. Find the area of the curved surface in cm2.

Answer 1

Answer:

$\large{\underline{\boxed{\mathfrak\blue{Curved \: surface \: area = 1318.8\: cm^2 }}}}$

$\rule{100}{2}$

Question:-

The diameter of the base of a right circular cylinder is 4.2 dm and it's height is 1 dm.Find the curved surface area in cm².

Given:-

• Diameter of circular cylinder = 4.2 dm
• Height of cylinder = 1 dm

To find:-

• Curved surface area = ?

We know,

$\star\large{\boxed{\sf\blue{CSA\: of \: cylinder = 2 \pi rh }}}$

$\frak{Here}\begin{cases}\sf{r \: denotes \:radius}\\\sf{h \: denotes \: height}\end{cases}$

$\rule{200}{1}$

Now,

➳ Radius of cylinder = Diameter/2

➳ Radius of cylinder = 4.2/2

➳ Radius of cylinder = 2.1 dm

➳ Radius of cylinder = (2.1 × 10) cm

$\scriptsize\sf\red{\: \: \: \: \: \: \: \: [\because 1\: dm = 10 \: cm]}$

➳ Radius of cylinder = 21 cm

$\rule{100}{1}$

Now,

➜ Height of cylinder = 1 dm

➜ Height of cylinder = (1 × 10) cm

➜ Height of cylinder = 10 cm

$\rule{100}{1}$

➤ CSA of cylinder = 2πrh

➤ CSA of cylinder =2 × 3.14 × 21 × 10

➤ CSA of cylinder = 1318.8 cm²

$\therefore{\boxed{\sf\red{Curved \: surface \: area \: of \: cylinder = 1318.8\: cm^2 }}}$

Answer 2

Answer:

Given:

The diameter of the base of a right circular cylinder in 4.2 dm and it's height is 1 dm.

Find:

Find the area of the curved surface in cm².

Using formula:

${\boxed{\tt{ CSA \: of \: cylinder\: 2 \pi r h}}}$

${\boxed{\tt radius \: of \: cylinder =\dfrac{Diameter}{2}}}}$

Know terms:

(CSA) = Curved surface are.

(R) = Radius.

(H) = Height.

(dm) = decimeters

Calculations:

[ Radius of cylinder ]

$\tt\rightarrow r = \dfrac{4.2}{2}$

$\tt\rightarrow r = 2.1 dm$

$\tt\rightarrow r = (2.1 \times 10) cm$

$\tt\rightarrow r = 21 cm$

[ Height of cylinder ]

$\tt\rightarrow h = 1 dm$

$\tt\rightarrow h = (1 \times 10) = 10 cm$

[ CSA of cylinder ]

$\tt\rightarrow CSA = 2 \times 3.14 \times 21 \times 10$

$\tt\rightarrow CSA = 1318.8 cm^2$

Therefore, 1318.8 cm² is the CSA of cylinder.