1. The problem statement, all variables and given/known data Let p1 = (4,0,4), p2 = (2,-1,8) and p3 = (1, 2, 3). Specify the condition that p = (x,y,z) lies in the plane of p1, p2, p3 (as an equation in x, y, z). Equation of a plane has the form of Ax + By + Cz + D = 0. (There were some other questions before this about finding the normal to the plane and area of the triangle formed by the 3 points which I have completed). 2. The attempt at a solution I'm not sure where to start here. The normal vector I have is <s>(-7, -9, -7)</s> (-7, -14, -7) which I think is correct. I think I somehow need to incorporate it into the general equation Ax+By+Cz+D=0, but don't know how. Any help is very much appreciated.