Question

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​

Answer 1

Answer:

Step-by-step explanation:

Here, h = 77 cm,

Outer radius (R) = 4. 4/ 2 cm = 2.2 cm,  Inner radius (r) = 4/ 2 cm = 2 cm

(i) Inner curved surface area of the pipe  = 2πrh

= 2 × 22/ 7 × 2 × 77 cm2  

= 2 × 22 × 22 cm2

= 968 cm2 Ans.

(ii) Outer curved surface area of the pipe = 2πRh

= 2 × 22/ 7 × 2.2 × 77 cm2

= 44 × 24.2 cm2  

= 1064.80 cm2 Ans.

(iii) Total surface area of the pipe = inner curved surface area + outer  curved surface area + areas of the two base rings.  

= 2πrh + 2πRh + 2π (R2 – r2)  

= 968 cm2 + 1064.80 cm2 + 2 × 22/ 7 [(2.2)2 – 22] cm2  = 2032.80 cm2 + 5.28 cm2

= 2038.08 cm2 Ans