Question

已知圆C与直线l1:x-y+m=0相切于点P(0,1),若圆心C在直线l2:3x+2y=0上,则圆C的方程是

Answer 1

L1:x-y+m=0,P(0,1)

y=x+m

x=0,y=m=1

CP:y=1-x

L2:3x+2y=0

3x+2*(1-x)=0

x=-2,y=3

C(-2,3),r^2=CP^2=8

(x+2)^2+(y-3)^2=8