Question

find the lateral surface area and the total surface area of the following cylinders
a) radius=21cm and height=45 cm
b)radius= 28cm and height = 28cm​

Answer 1

A) Radius = 21 cm and Height = 45 cm .

Given :

⬤ Radius of Cylinder is 21 cm.

⬤ Height of Cylinder is 45 cm.

To Find :

⬤ Lateral Surface Area of Cylinder.

⬤ Total Surface Area.

Formula Used :

$\bullet\:\begin{gathered}\bf[\:{Lateral \: Surface \: Area \: of \: Cylinder = 2\pi{r}h}\\\end{gathered}\:]$

$\bullet\:\begin{gathered}\bf[\:{Total \: Surface \: Area \: of \: Cylinder = 2\pi{r}\:(r+h)}\\\end{gathered}\:]$

Solution :

• Radius = 21
• Height = 45

Lateral Surface Area of Cylinder :-

2πrh

2 × 22/7 × 21 × 45

44 × 3 × 45

5940

Total Surface Area of Cylinder :-

2πr (r + h)

2 × 22/7 × 21 (21 + 45)

44 × 3 (21 + 45)

132 (66)

8712

Therefore , Lateral Surface Area of Cylinder is 5940 cm² and Total Surface Area of Cylinder is 8712 cm².

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B) Radius = 28 cm and Height = 28 cm.

• Radius = 28 cm
• Height = 28 cm

Lateral Surface Area of Cylinder :-

2πrh

2 × 22/7 × 28 × 28

44 × 28 × 4

4928

Total Surface Area of Cylinder :-

2πr (r + h)

2 × 22/7 × 28 (28 + 28)

44 × 4 (28 + 28)

176 (56)

9856

Therefore , Lateral Surface Area of Cylinder is 4928 cm² and Total Surface Area of Cylinder is 9856 cm².