# Homework Help: Equations of lines

1. Oct 5, 2007

1. The problem statement, all variables and given/known data
Find equations for a line perpendicular to both of these lines.

2. Relevant equations
(x/3)=(y/2)=(z/2) and (x/5)=(y/3)=(z-4)/2

3. The attempt at a solution

i dont know how to start???I know the two lines are skew, if i take the cross product will it be perp. to both lines??Can i take the cross product of two lines that lie in different planes?

Last edited: Oct 5, 2007
2. Oct 5, 2007

### Dick

You don't take the cross product of the lines. You take the cross product of the direction vectors of the lines. The result is a direction vector for the perpendicular line.

3. Oct 5, 2007

how do i find the direction vectors?

4. Oct 5, 2007

### Dick

Do you have a text book? Isn't it covered in there?

5. Oct 5, 2007

No!!My book leaves a lot of details out, it expects us to know certain calculus stuff since its a post calculus course.I just dont remember direction vectors but have studied them in the past.Ill see what i can find n google.thnx anyway.

6. Oct 5, 2007

### Dick

Then you may need another book to keep on hand. ax=by=cz has direction vector (1/a,1/b,1/c).

7. Oct 5, 2007