Question

A metal pipe is 77 cm long. The inner diameter of a cross section is 4 cm and thickness of metal is 2 cm.

Find its (i) inner curved surface area, (ii) outer curved surface area.

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Answer 1

Solution :-

(i)

Finding inner curved surface area

We will consider metal pipe as a cylinder

Inner diameter of a cross section (d) = 4 cm

So radius of a cross section (r) = d/2 = 4/2 = 2 cm

Height of the metal pipe (h) = 77 cm

Inner curved surface area = 2πrh

= 2 * (22/7) * 2 * 77

= 44 * 2 * 11

= 44 * 22

= 968 cm²

Therefore Inner curved surface area is 968 cm²

(ii)

Finding outer curved surface area

Inner radius of cross section = 2 cm

Thickness of the metal = 2 cm

Outer radius of cross section (r) = Inner radius + Thickness of the metal = 2 + 2 = 4 cm

Height of the metal pipe (h) = 77 cm

Outer curved surface area = 2πrh

= 2 * (22/7) * 4 * 77

= 44 * 4 * 11

= 44 * 44

= 1936 cm²

Therefore the outer curved surface area is 1936 cm²

Answer 2

Answer:

${\pink{\green{\sf{\therefore Inner\:C.S.A=968cm^{2}}}}}$

${\pink{\green{\sf{\therefore Outer\:C.S.A=1936cm^{2}}}}}$

Step-by-step explanation:

$\huge{\pink{\green{\underline{\red{\sf{SOLUTION-}}}}}}$

• In the given question information given about a cylindrical pipe whose inner diameter is given and thickness of pipe is given.

• So we have to find Inner C.S.A and Outer C.S.A.

$\underline \bold{Given : } \\ \implies Height \: of \: pipe = 77cm \: \\ \implies Inner \: radius = \frac{4}{2} = 2cm \\ \implies Outer \: radius = 2 + 2 = 4cm \\ \\ \underline \bold{To \: Find : } \\ \implies Inner \: curved \: surface \: area = ? \\ \implies Outer \: curved \: surface \: Area = ?$

• According to given question :

$\bold{for \: inner \: curved \: surface \: area} \\ \implies Inner \: C.S.A =2 \pi {r} h \\ \implies Inner \: Area = 2 \times \frac{22}{7} \times 2 \times 77 \\ \bold{\implies Inner \: Area = 968 {cm}^{2} } \\ \\ \bold {for \: Outer \:curved \: surface \: Area} \\ \implies outer \: Area = 2\pi rh \\ \implies Outer \: Area = 2 \times \frac{22}{7} \times 4 \times 77 \\ \bold{\implies Outer \: Area = 1936 {cm}^{2} }$