SOLUTION: what is the approximate surface area of an open piece of pipe with a radius of 4 cm and a length of 9 cm?

Question 381349: what is the approximate surface area of an open piece of pipe with a radius of 4 cm and a length of 9 cm?
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
If it's a pipe then I'll assume the ends are open and we can count the inner surface area.
The "lateral" surface area is the circumference times the height, i.e. (9 cm)(8pi cm) = 72pi sq cm.
If we count the inner surface area then the surface area is double that, or 144pi sq cm.

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