Height of cylinder (h) = Length of cylindrical pipe = 28 m or 2800 cm [1 m = 100 cm]
Diameter of circular end of pipe = 5 cm
Let ‘r’ be the radius of circular end, then
r = diameter/2 = 5/2 cm
We know,
Curved surface area of cylindrical pipe = 2πrh
= 2 x 3.14 x 5/2 x 2800
= 44000
Therefore, the area of radiating surface is 44000 cm2.