Question

Radius of base of a cylinder and its height are given.Then find the curved surface area and total surface area

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Answer 1

Answer:

1. Curved surface area of the cylinder = 110 cm²
2. Total surface area of the cylinder = 149.28 cm²

Given:

• Radius of base of a cylinder = 2.5 cm
• Height of cylinder = 7 cm

To Find:

1. Curved surface area of the cylinder = ??
2. Total surface area of the cylinder = ??

Process:

1. To find the curved surface area of the cylinder we need radius of the base of the cylinder and the height of the cylinder, which are given. Then, we can use a formula which is - (2πrh) sq. units. Where, r stands for radius and h stands for height.
2. To find the total surface area of the cylinder we also need radius and height of the cylinder, which are given. Then, we can use a formula which is - {2πr(h + r)} sq. units. Where, r stands for radius and h stands for height.

Solution:

1) Curved surface area of the cylinder = (2πrh) sq. units

= (2 × 22/7 × 2.5 × 7) cm²

= (2 × 22 × 2.5) cm²

= 110 cm²

Hence, curved surface area of the cylinder is 110 cm².

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2) Total surface area of the cylinder = {2πr(h + r)} sq. units

= {2 × 22/7 × 2.5(7 + 2.5)} cm²

= {2 × 22/7 × 2.5 × 9.5} cm²

= {1045/7} cm²

= 149.29 cm²

Hence, total surface area of the cylinder is 149.29 cm².

Answer 2

Given :-

• Radius of base of cylinder = 2.5cm
• Height of cylinder = 7cm

To find :-

• Curved surface area of cylinder
• Total surface area of cylinder

Formulae to be used :-

• Curved surface area of cylinder = 2πrh
• T.S.A of cylinder = 2πr (r + h)

where,

• R = radius
• H = height

Solution :-

(i) Finding C.S.A of cylinder :-

C.S.A of cylinder, = 2πrh

C.S.A = 2 × 22/7 × 2.5 × 7

C.S.A = 44 × 2.5

C.S.A = 110 cm²

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(ii) Finding T.S.A of cylinder :-

T.S.A of cylinder = 2πr (r + h)

T.S.A = 2 × 22/7 × 2.5 ( 2.5 + 7)

T.S.A = 110/7 × 9.5

T.S.A = 149.29 cm²