Q(x,y)
xA+xB=x+a,yA+yB=y+b
[(yA-b)/(xA-a)]*[(yB-b)/(xB-a)]=-1
xA*xB+yA*yB-a*(xA+xB)-b(yA+yB)+a^2+b^2=0
xA*xB+yA*yB=a*(x+a)+b(y+b)-a^2-b^2=ax+by
(xA+xB)^2+(yA+yB)^2=(x+a)^2+(y+b)^2
(xA)^2+(yA)^2+(xB)^2+(yB)^2+2(xA*xB+yA*yB)=(x+a)^2+(y+b)^2
r^2+r^2+2(ax+by)=(x+a)^2+(y+b)^2
x^2+y^2=2r^2-a^2-b^2