1. The problem statement, all variables and given/known data Points (-3, -1, 4), (0, -1, -2), (2, 5, 1), (3, 2, 7) and (5, 1, -2) are the vertexes of an 3D quadrilateral. Find four points which are on a plane in the 3D quadrilateral. 3. The attempt at a solution I know that you can find the points by counting the normal vector of two given vectors and then multiplying this with the given vector, not one in the cross product. If the dot product is zero for each vector, then you have found the plane. However, this takes many steps to count. The correct answer to the question is apparently ABDC. How can you find efficiently the plane?