Question

Radius of base of a cylinder is 20cm and its height is 13cm ,find its curved surface area and total surface area (=22÷7

Answer 1

$\bold{\sf{\underline{\underline{\huge{AnsWer:}}}}}$

Curved surface area = 1634.28 cm²

Total surface area = 4148.57 cm²

$\bold{\sf{\underline{\underline{\large{StEp\:by\:stEp\:explanation:}}}}}$

GiVeN :

• Radius of base of a cylinder is 20 cm
• Height of the cylinder is 13 cm
• $\pi$ = $\sf{\dfrac{22}{7}}$

To FiNd :

• Curved surface area
• Total surface area

SoLuTiOn :

So to calculate the curved surface area, we have the formula :

$\bold{\large{\boxed{\green{\tt{Cured\:surface\:area\:of\:cylinder\:=\:2\:\pi\:r\:h}}}}}$

Where,

• r = radius = 20 cm
• h = height = 13 cm

Block in the values,

$\longrightarrow$ $\rm{2\:\times\:{\dfrac{22}{7}\:\times\:20\:\times\:13}}$

$\longrightarrow$ $\sf{\dfrac{44\:\times\:20\:\times\:13}{7}}$

$\longrightarrow$ $\sf{\dfrac{880\:\times\:13}{7}}$

$\longrightarrow$ $\sf{\dfrac{11440}{7}}$

$\longrightarrow$ $\sf{1634.28\:sq.cm}$

$\sf{\therefore{Curved\:surface\:area\:of\:cylinder\:=\:1634.28\:cm^2}}$

ToTaL sUrFaCe ArEa :

We have the formula,

$\bold{\large{\boxed{\pink{\sf{Total\:surface\:area\:of\:cylinder\:=\:2\:\pi\:r\:(r\:+\:h)}}}}}$

Block in the values,

$\longrightarrow$ $\sf{2\:\times\:{\dfrac{22}{7}\:20\:(20\:+\:13)}}$

$\longrightarrow$ $\sf{\dfrac{44\:\times\:20\:\times\:33}{7}}$

$\longrightarrow$ $\sf{\dfrac{29040}{7}}$

$\longrightarrow$ $\sf{4148.57\:sq.cm}$

$\sf{\therefore{Total\:surface\:area\:of\:cylinder\:=\:4148.57\:cm^2}}$

Answer 2

SOLUTION:-

Given:

The radius of base of a cylinder is 20cm & it's height of a cylinder is 13cm.

To find:

•Its curved surface area of cylinder &

•Total surface area of cylinder.

Explanation:

Formula: Curved surface area of cylinder

Formula: 2πrh

We have,

• Height of the cylinder,h=13cm
• Radius of the cylinder,r= 20cm

$= > (2 \times \frac{22}{7} \times 20 \times 13) {cm}^{2} \\ \\ = > (\frac{44}{7} \times 260) {cm}^{2} \\ \\ = > ( \frac{11440}{7} ) {cm}^{2} \\ \\ = > 1634.28 {cm}^{2}$

&

Formula: Total surface area of the cylinder

Formula: 2πr² + 2πrh

Therefore,

$= > 2 \times \frac{22}{7} \times 20 \times 20 + 2 \times \frac{22}{7} \times 20 \times 13 \\ \\ = > \frac{44}{7} \times 400cm + \frac{44}{7} \times 260cm \\ \\ = > \frac{17600}{7} {cm}^{2} \: + \frac{11440}{7} {cm}^{2} \\ \\ = > 2514.28 {cm}^{2} + 1634.28 {cm}^{2} \\ \\ = > 4148.56 {cm}^{2}$

Thus,

•The curved surface area of cylinder is 1634.28cm².

•The total surface area of the cylinder is 4148.56cm².