Question

3. Find the volume, curved surface area and total surface area of cach of the cylinders whose dimensions are
given below:
(ii) Radius of the base = 2.8 dm, height = 0.8 dm
​

Answer 1

Given:

A cylinder with

• Radius = 2.8 dm
• Height = 0.8 dm

What To Find:

We have to find the

• Volume
• Curved surface area (CSA)
• Total surface area (TSA)

Formula:

• Volume = πr²h
• CSA = 2πrh
• TSA = 2πr (h + r)

Solution:

• Finding volume,

Using the formula,

⇒ Volume = πr²h

Substitute the values,

⇒ $\sf{Volume = \dfrac{22}{7} \times 2.8 \times 2.8 \times 0.8}$

Cancel 2.8 and 7,

⇒ Volume = 22 × 0.4 × 2.8 × 0.8

Multiply,

⇒ Volume = 19.712 dm³

• Finding CSA.

Using the formula,

⇒ CSA = 2πrh

Substitute the values,

⇒ $\sf{CSA = 2 \times \dfrac{22}{7} \times 2.8 \times 0.8}$

Cancel 2.8 and 7,

⇒ CSA = 2 × 22 × 0.4 × 0.8

Multiply,

⇒ CSA = 14.08 dm²

• Finding TSA

Using the formula,

⇒ TSA = 2πr (h + r)

Substitute the value,

⇒ $\sf{TSA = 2 \times \dfrac{22}{7} \times 2.8 (0.8 + 2.8)}$

Solve the brackets,

⇒ $\sf{TSA = 2 \times \dfrac{22}{7} \times 2.8 \times 3.6}$

Cancel 7 and 2.8,

⇒ TSA = 2 × 22 × 0.4 × 3.6

Multiply,

⇒ TSA = 63.36 dm²