1. I basicly have to find the coordinates of P. All the pink lines are know, coordinates of points A and centre of circle are know. 2. (x-a)^2 + (y-b)^2 = r^2 3. I try to substitute mx+c into the equation and get (x-a)^2 + (y-mx-c)^2 + r^2= 0 but I cant work out what m and c are. Any help would be appreciated! Am I in the right direction, or am I completely off?