half or quarter of cylinder
circle
The parametric equation of a circle with radius r is:
x = r . cos
y = r . sin
with from 0 to 360°
cylinder
If we add a linear parameter h for z we can define a cylinder:
x = r . cos
y = r . sin
z = h
with from 0 to 360° and h from 0 to the height of the cylinder.
Shuffling the three expressions we can make the cylinder standing up or lying down.
Changing the Start and/or End Value of the angle, we can create e.g. a half or a quarter of a cylinder.
The GeoGebra command to draw such parametric surfaces is:
Surface( , , , , , , , , )