A metalic pipe is 0.7 cm thick.Inner radious of the pipe is 3.5 cm and length is 5 dm.Find. Find its total surface area

Answer 1

I see 2 rectangle shaped areas, one for the inside of the pipe, the other
for the outside of the pipe, plus 2 washer-shaped ends
SA = 2π(3.5) + 2π(4.2) + 2(π(4.2)^2 - π(3.5)^2 )
= 2π( 3.5 + 4.2 + 4.2^2 - 3.5^2)
= ....