Question

已知a点坐标（0,8）直线 x-2y-4=0与y轴交于b点,p为直线上动点

Answer 1

A(0,8),B(0,-2)

(0-a)^2+(8-b)^2=r^2.(1)

(0-a)^2+(-2-b)^2=r^2.(2)

(a-2b-4)^2/5+(6√5/2)^2=r^2.(3)

a=5,-10,b=3,r^2=50,125

(x-5)^2+(y-3)^2=50

(x+10)^2+(y-3)^2=125