Length of metal pipe, l = 77 cm,
h = 77 cm.
Inner diameter = 4 cm,
∴ r1 = 2 cm.
Outer diameter= 4.4 cm.
∴ r2 = 2.2 cm.
(i) Inner surfce area of pipe (C.S.A) = 2πr1h
= 2 × 22 × 2 × 11 = 968 cm2 .
(ii) Outer surface area of pipe (C.S.A) = 2πr2h
= 2 × 22 × 2.2 × 11 = 44 × 24.2 = 1064.8 cm2 .
(iii) Total Surface area of Pipe (T.S.A.)
= Inner CSA + Outer CSA + Area of circular ring.
= 2πr1h + 2πr2h + (2πr2 2h – 2πr1 2h)
= 2032.8 + 5.28
∴ T.S.A. = 2038.08 cm2 .