Math, asked by Ambika8369, 6 months ago

3) A metal pipe is 77 cm long. The inner diameter of a cross
section is 4 cm, the outer diameter being 4.4 cm
(see Fig. 13.11). Find its
6) inner curved surface area,
(i) outer curved surface area,
(mi) total surface area.​

Answers

Answered by brotin098
3

(i) inner curved surface area

According to the question inner diameter is 4 cm,

then,

Inner radius of a cylindrical pipe =r

1

=

2

innnerdiameter

=(

2

4

)cm=2cm

Height (h) of cylindrical pipe=77 cm,

Curved Surface Area of inner surface of pipe =2πr

1

h

=(2×

7

22

×2×77)cm

2

=968cm

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A metal pipe is 77 cm long....

MATHS

A metal pipe is 77 cm long. The inner diameter of a cross section is 4 cm, the outer diameter being 4.4 cm (see Fig. 13.11). Find its

(i) inner curved surface area,

(ii) outer curved surface area,

(iii) total surface area.

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ANSWER

(i) inner curved surface area

According to the question inner diameter is 4 cm,

then,

Inner radius of a cylindrical pipe =r

1

=

2

innnerdiameter

=(

2

4

)cm=2cm

Height (h) of cylindrical pipe=77 cm,

Curved Surface Area of inner surface of pipe =2πr

1

h

=(2×

7

22

×2×77)cm

2

=968cm

2

(ii) Outer curved surface area

According to the question outer diameter is 4.4 cm

Outer radius of cylindrical pipe =r

2

=

2

outerdiamterer

=(

2

4.4

)cm=2.2cm

Height of cylinder = h = 77 cm,

Curved area of outer surface of pipe = 2πr

h

=(2×

7

22

×2.2×77)cm

2

=(2×22×2.2×11)cm

2

=1064.8cm

iii) Total surface area

Total surface area = curved surface area of inner cylinder + curved surface of outer cylinder + 2 × Area of base

Area of base = area of circle with radius 2.2 cm - Area of circle with radius 2 cm

=πr

2

2

−πr

1

2

=

7

22

×((2.2)

2

−(2)

2

)

=

7

22

×(4.84−4)

=

7

22

×(0.84)

=2.74cm

2

Total surface area = curved surface area of inner cylinder + curved surface area of outer cylinder + 2 × Area of base

=968+1064.8+2×2.74

= 2032.8 + 5.76

=2039.08cm

2

Therefore, the total surface area of the cylindrical pipe is

=2039.08cm

2

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