Question

圆与直线 圆M：x^2+y^2-4x-2y+4=0 从圆外一点p(a,b),从该圆引切线PA,切点为A,且PA=PO,

Answer 1

x²+y²-(2+a）x-(3-2a)y+2=0

x²+y²-2x-3y+2-ax+2ay=0

x²+y²-2x-3y+2-a(x-2y)=0

∴x²+y²-2x-3y=0,x-2y=0.