In general, area is easier to solve in 1D than in higher dimensions. So if you imagine you are going to make a cylinder out of paper, you can make the object with a single cut and two folds. Now it should be easy to see that the surface area is just 2 circles plus 1 rectangle. The rectangle comes from the height and circumference of the cylinder and thus takes the dimensions of 2πr×h . The area of the 2 circles is simply 2πr2 . So the total surface area is 2π42+2π(4)(12)=128πcm²
