def triangle_normal ( a , b , c ) : normal = np . cross ( a - c , b - c ) norm = np . linalg . norm ( normal ) return normal / norm
python calc normal of 3d points
Return a vector orthogonal to the given triangle
def triangle_normal(a, b, c):
    """Return a vector orthogonal to the given triangle

       Arguments:
         a, b, c  --  three 3D numpy vectors
    """
    normal = np.cross(a - c, b - c)
    norm = np.linalg.norm(normal)
    return normal/norm