平行不重合A1B2=A2B1且C1B2≠C2B1
相交:A1B2≠A2B1
垂直:B1B2≠0时,A1A2=-B1B2
B1=0,A2=0或B2=0,A1=0
重合:A1B2=A2B1且C1B2=C2B1