Question

a metal pipe is 77 CM long, the inner diameter of the cross section is 4 CM and the outer diameter is 4.8 CM. Find the (i) inner curved surface area (ii) outer curved surface area (iii) total surface area​

Answer 1

Given:-

• A metal pipe is 77 cm long, the inner diameter of the cross section is 4 cm and the outer diameter is 4.8 cm.

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To find:-

• inner curved surface area
• Outer curved surface area.
• Total surface area.

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Solution:-

→ Radius = 4/2

→ r = 2 cm

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→ CSA = 2πr_1h

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→ 2 × 22/7 × 2 × 77

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→ 968 cm²

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Hence,

• CSA (inner) = 968 cm²

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Now,

→ Radius = 4.4/2

→ r = 2.2 cm

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→ CSA = 2πr_2h

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→ 2 × 22/7 × 2.2 × 77

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→ 2 × 22 × 2.2 × 11

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→ 1064.8 cm²

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Hence,

• CSA (outer) = 1064.8 cm²

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Now,

→ 22/7 × ((2.2)² - (2)²)

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→ 22/7 × (4.84 - 4)

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→ 22/7 × 0.84

→ 2.64 cm²

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Then,

→ 968 + 1064.8 + 2 × 2.64

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→ 2032.8 + 5.28

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→ 2038.08 cm²

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Hence,

• TSA = 2038.08 cm²