# Homework Help: Given a 3D vector, how to find the angle it forms with a plane?

1. Oct 10, 2009

### KingNothing

Say I'm given a random 3-dimensional vector, pointing from the origin. How can I find the angle it forms with a plane defined by two other vectors?

2. Oct 10, 2009

### D H

Staff Emeritus
This looks like homework. If it is, you should have posted in the homework section -- and shown some work.

3. Oct 11, 2009

### D H

Staff Emeritus
Use the angle between the line and a normal to the plane.