Question

how do you find the surface area of a cylinder

Answer 1

Area of the top and bottom = \[2 * \Pi * r^2\]
For the cylider height, Take the differential dx of a wall of height y. The number of strips is 2 Pi. The radius is x. The area of the outer wall is \[2 * \Pi * xy dx\]

Area of a cylinder = \[(2 * \Pi * r^ 2) + (2 * \Pi * x * y)\]

Answer 2

I should have put x squared instead of r squared