Question

A cylinder of radius 7cm and height 20cm is to be formed using card seat find the area of card sheet which is required.

Answer 1

Given :

• Radius of cylinder = 7 cm
• Height of cylinder = 20 cm

To Find :

• Area of card sheet required to form a cylinder.

Concept :

The card sheet is in the form of rectangular sheet, so it can be rolled to form a cylinder of required radius and height. Hence we need to find the Lateral surface area of cylinder.

Solution :

Let radius be r and height as h.

We know,

$Lateral \: surface \: area \: of \: cylinder = 2\pi rh$

Now, on putting the required values of r and h we have ;

$Lateral \: surface \: area \: of \: cylinder = 2 \times \frac{22}{7} \times 7 \times 20 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 44 \times 20 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = 880 \:$

Therefore, the area of card sheet required to form a cylinder is 880 cm ².

Answer 2

$\huge\sf\red{Answer:}$

Given:

⇒ A cylinder of radius 7cm and height 20cm is to be formed using card seat.

Find:

⇒ Find the area of card sheet which is required.

Using formula:

★ ${\sf{\underline{\boxed{\green{\sf{Lateral \: surface \: area = 2πrh}}}}}}$

Calculations:

⇒ $\sf \cancel{2} \times \cancel{\dfrac{22}{7}} \times \cancel{7}$

⇒ $\sf 44 \times 20$

⇒ ${\sf{\underline{\boxed{\green{\sf{880 \: cm^2}}}}}}$

Therefore, 880 cm² is the area of card sheet required to form a cylinder.