A ruled surface is one that can be generated by the movement of a
straight line. The straight line in motion, in any of its positions, is called the surface generatrix.
A ruled surface is generated by a straight line that moves in such a way that it always remains
parallel to the XZ plane and cuts to the line z = 2, x = 0 and the circumference {2 Cos[t], 2 Sin[t], 0}.