Summary: 12.6 Cylinders and Quadric surfaces
Cylindrical Surfaces
Any equation that contains only two variables represents a
cylindrical surface in 3dimensional coordinate system
Graph it in 2dimensions
Extend the graph to the missing axis
How to draw the graph?
2
y x=
1
Exercise: Sketch the graph 2 2
1x y+ = in and2 3
Solution
in 2
· a circle of radius `1' centered at origin
in 3
· can take any valuez
· for every value of we have a circle of radius `1' centered at Zaxisz
· we have infinitely many copies of circles sitting over each other
1
