Ok here's one for you.

I'm gonna have an exam out of these things in three days and I've been having trouble with surface generation problems.

Code:

```
Write the equation of a circular cilindrical surface which contains the lines:
x=y=z
x+1=y=z-1
x-1=y+1=z-2
```

Ok , so far I know the direction, the generators, and I need the directrix curve which should be a circle that contains the intersection points of those lines with a plane perpendicular to them.Those 3 points form a triangle that "fits right into my circle" (lol , I don't know the mathematical term in english

) . I need the coordinates for the center of that circle and its radius.The perpendicular plane is also easily obtainable.

Anyone care to help? :

Btw, what kind of math do you guys study at college? I'm just a first year at robotics.I study some algebra(determinants, gauss-jordan method) , analytic geometry^ , and analysis (partial derivatives, integrals, differentials, Taylor ,macLaurin).And some differential geometry next semester.