Question

A metallic pipe is 0.7 cm thick. lnner radius of the pipe is 3.5 c
m and length is 5 dm. find its total surface area.

Answer 1

that would be the area of the inner cylinder, plus the area of the outer cylinder, plus the area of the two rings at the end. So, if

R = outer radius

r = inner radius

h = length of pipe

the total area is

2πrh + 2πRh + π(R^2-r^2)

= 2πh(r+R) + π(R+r)(R-r)

= π(R+r)(2h+R-r)