圆C：(x+2)^2+y^2=1,圆心(-2,0)半径1(1)：(y-2)/(x-1)相当于过点P(x,y)(1,2)直线的斜率.所以作图可知相切时有极值.记k=(y-2)/(x-1),即是kx-y-k+2=0,根据点到直线的距离,(-2,0)到直线kx-y-k+2=0有...