1. The problem statement, all variables and given/known data Sketch the locus of points in the argand diagram defined by z: arg (z-1) - arg(z+1) = ∏/4 2. Relevant equations 3. The attempt at a solution By simple geometry i worked out that at a point in the x-y plane, the angle subtended from that point to -1 and 1 must be = pi/4. For a circle I know this must be = pi/2. But for pi/4 I have no clue..