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## Main Question or Discussion Point

**Calculating Surface area/volume from 2D cross section??**

I'm feeling a little stupid today and I need some help...:tongue2:

Assume that I have a radially-symmetric 3D object (for example a candle stick or the base of a table lamp) and that I can calculate the surface area of the largest longitudinal cross section (ie, I split the object precisely along the axis of radial symmety and measure the area of the newly exposed surface). Also assume that the outside profile of this object can be described by a function (though I do not know what the function is)

Is there any reason that I cannot then treat this object as the cross section of a simple cylinder, the product of whose length and diameter is equal to my object's cross sectional surface? In other words, if my object's cross sectional area turned out to be 10 square units with a length of 5), then can I say that my object's volume is equal to the volume of a cylinder with length 5 and diameter 2?

EDIT: corrected an error

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