Q : 3    A metal pipe is \small 77\hspace{1mm}cm long. The inner diameter of a cross section is \small 4\hspace{1mm}cm, the outerdiameter being  \small 4.4\hspace{1mm}cm (see Fig. \small 13.11). Find its

              (ii) Outer surface area.

                

Answers (1)
N Nehul

Note: There are two surfaces, inner and outer.

Given,

Height of the cylinder, h = 77\ cm

Outer diameter  = r_1 = 4.4\ cm

Inner diameter  = r_2 = 4\ cm

Outer curved surface area = 2\pi r_1h

\\ = 2\times\frac{22}{7}\times2.2\times77 \\ = 1064.8\ cm^2

Therefore, the outer curved surface area of the cylindrical pipe is 1064.8\ cm^2

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