Equation of bisectors are given by x−y=0 and x+y+z=0 Bisector intersect at the point P(−1,−1) Focus S, is the foot of parallel from P to MN Where M(1,1) and N(0,−2) MN⇒3x−y−z=0,PS=x+3y+4=0 ∴ Focus =(
1
5
,
−7
5
),MS=√
2
5
,NS=4√
2
5
LR=
16√2
53∕2
Circle through PMN is x2+y2−x+y−2=0 Equation of directrix = equation of tangents at (−1,−1) is 3x+y+4=0
