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

(i) Inner curved surface area,


(ii) Outer curved surface area,


(iii) Total surface area


Inner radius (r1) = = 2 cm

Outer radius (r2) = = 2.2 cm


Height = Length = 77 cm


(i) CSA of inner surface of pipe:


= 2r1h


= (2 * * 2 * 77) cm2


= 968 cm2


(ii) CSA of outer surface of pipe


= 2πr2h


= (2 * * 2.2 * 77) cm2


= (22 * 22 * 2.2) cm2


= 1064.8 cm2


(iii) TSA = Inner CSA + Outer CSA + Area of both circular ends of pipe


= 2πr1h + 2πr2h + 2π (r22 – r12)


= [968 + 1064.8 + 2π {(2.2)2 - (2)2}] cm2


= (2032.8 + 2 * * 0.84) cm2


= (2032.8 + 5.28) cm2


= 2038.08 cm2


Therefore, the total surface area of the cylindrical pipe is 2038.08 cm2


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