# Surface angle

Printable View

• May 15th 2006, 10:30 PM
Daniel Smith
Surface angle
I need to find out two agles with from 3D triangle which I have the co-ordinates for. I need to find out which direction the triangle is sloping (in degrees) and what ang it is sloping at.
I would put an image in to help describe but I dont know how to.

Any ideas?
• May 15th 2006, 11:03 PM
JakeD
The vector cross product does what you're looking for. When $a$ and $b$ are vectors describing the triangle, $a \times b$ is a vector that is perpendicular (orthogonal) to the plane of the triangle, so it tells you the direction and angle of that plane.
http://upload.wikimedia.org/wikipedi...ossproduct.png
• May 15th 2006, 11:18 PM
Daniel Smith
Thanks, thats just what i was looking for.