The vector cross product does what you're looking for. When and are vectors describing the triangle, is a vector that is perpendicular (orthogonal) to the plane of the triangle, so it tells you the direction and angle of that plane.
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.