Question

Ametal pipe is 77 cm long,the inner diameter of the cross- section is 4 cm and the outer diameter is 4.8 cm. Find the (a)inner curved surface area, (b)outer curved surface area & (c) total surface area?

Answer given on back of the book is (a)968cm square &(b) 1161.6 cm square & (c) 2140.66 cm square​

Answer 1

Step-by-step explanation:

Let

Inner radius = r

Outer radius =R

Formula for CSA of a cylinder = 2πrh

= 2×22/7×2×77

= 2×22×2×11

= 242×2×2

= 484×2

= 968 cm^2 = inner CSA

Outer CSA = 2πRh

= 2×22/7×2.4×77

= 2×11×2.4×22

= 242×4.8

= 1161.6 cm^2

TSA = (outer CSA + inner CSA) +

{2π (R^2 - r^2)}

= (968+1161.6) +{2×22/7(5.76-4)

= 2129.6 + {44/7×1.76}

= 2129.6 + (6.28×1.76)

= 2129.6 + 11.07

= 2140.66 cm^2