C:x^2+y^2-2y=4C(0,1),r=√5y-3=k*(x-3)kx-y+3-3k=0|0-1+3-3k|/√(1+k^2)=r=√5k=1.5±0.5√10y-3=(1.5±0.5√10)*(x-3)
