you have 3 points, so you can make 2 vectors. if you take their cross product, you can get the normal for the plane. this should be enough to use plane source. You could set the center of the plane as the center of the triangle, then set the normal.
you have 3 points, so you can make 2 vectors. if you take their cross product, you can get the normal for the plane. this should be enough to use plane source. You could set the center of the plane as the center of the triangle, then set the normal.