Perhaps you want to paint the outside of the pipe and you need to know its area? A cylinder has an area that is the circumference multiplied by the length. Of course, the circumference is Pi times the diameter. Since we don't know much about your pipe, we will assume the diameter of the area you are interested in is 3 inches = 1/4 foot.

So,

Area = (42 feet)(Pi)(1/4 foot)

= 10.5 Pi ft

= about 33 ft

Unless we know something about the pipe material, thickness, density, weight/foot, or other information related to weight, we cannot begin to guess what your pipe may weigh. A plastic 3" pipe will weigh substantially less than a cast iron 3" pipe.

So,

Area = (42 feet)(Pi)(1/4 foot)

= 10.5 Pi ft

^{2}= about 33 ft

^{2}.Unless we know something about the pipe material, thickness, density, weight/foot, or other information related to weight, we cannot begin to guess what your pipe may weigh. A plastic 3" pipe will weigh substantially less than a cast iron 3" pipe.