A(4,0),B(0,2)C(x,y)(x-4)^2+y^2=4^2+2^2.....(1)x^2+(y-2)^2=2*(4^2+2^2)...(2)(1)-(2),得2x-y=8y=2x+8代入1得5x^2+24x-36=0x=-6 y=-4 BC的解析式(y+4)/4=(x+6)/4 y=x+2x=6/5 y=52/5 BC的解析式(y-52/5)/(2-52/5)=(x-6/5)/(4 -6/5) y=x+36/5