Equation of the rectangular hyperbola whose focus is (1,-1) and the corresponding directrix is x - y + 1 = 0 is
x2−y2=1
xy = 1
2xy - 4x + 4y + 1 =0
2xy + 4x - 4y - 1 = 0
Eccentricity of rectangular hyperbola is 2
∴ Equation of hyperbola is
(x−1)2+(y+1)2=2|x−y+1|12+(−1)2
or (x−1)2+(y+1)2=(x−y+1)2or 2xy−4x+4y+1=0