Lingkaran x²+y²-2x+2y-3=0 dicerminkan terhadap y=-x
A(x,y) My = -x A'(x',y')
x' = -y
y'=-x
subtitusikan
(-y)² + (-x)² -2(-y) + 2(-x) -3 = 0
y² + x² +2y -2x -3 = 0
Lingkaran x²+y²-2x+2y-3=0 dicerminkan terhadap y=-x
A(x,y) My = -x A'(x',y')
x' = -y
y'=-x
subtitusikan
(-y)² + (-x)² -2(-y) + 2(-x) -3 = 0
y² + x² +2y -2x -3 = 0