Question

12. What is the surface generated by a straight line that moves along a fixed curve, and which remains parallel to a fixed-line not on the curve?

Answer 1

The surface generated by a variable line which remains parallel to a fixed line and intersects a given curve (or touches a given surface) is called a cylinder.

The variable line is called the generator, the fixed straight line is called the axis of the cylinder and the given curve is called the guiding curve of the cylinder.