The plane P1 contains the points A,B,C, which have position vectors a=(0,0,0), b=(1,1,8) and c=(0,1,5) respectively. Plane P2 passes through A and is orthogonal to the line BC, whilst plane P3 passes through B an is orthogonal to the line AC. Find the coordinates of r, the point of intersection of the three planes
The Attempt at a Solution
I have found the equation of plane P1 using the vector product of vectors AB and AC, but I can't find the equation of the line perpendicular to BC which passes through A to find plane P2.
Can anyone help?