Surface area of a cylinder is 2πr² + 2πrh: two bases plus the wrapper. Radius 3 and height 4 give 18π + 24π = 42π. Surface area as a set is in surface area.
Wrap versus fill
Volume of the same cylinder is πr²h, in volume of a cylinder. If the question is paint or label, you want surface. If it is how much it holds, you want volume.
A pyramid is a one-third volume, in volume of a pyramid. The short list is in ACT Math formulas.
The bottom line
Two circles plus the rectangle wrapper: 2πr² + 2πrh.
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