________当https://bgk-photo.cdn.bcebos.com/2e2eb9389b504fc2a6648764f5dde71190ef6d93.jpg平行时，https://bgk-photo.cdn.bcebos.com/43a7d933c895d1437455d34263f082025aaf07ab.jpg且https://bgk-photo.cdn.bcebos.com/72f082025aafa40f94e5f9bcbb64034f78f019ab.jpg；重合时，https://bgk-photo.cdn.bcebos.com/b58f8c5494eef01fb92f2fa4f0fe9925bc317d93.jpg;相交时，https://bgk-photo.cdn.bcebos.com/9825bc315c6034a8d4d98fe0db13495409237693.jpg;垂直时，https://bgk-photo.cdn.bcebos.com/48540923dd54564e035ed358a3de9c82d1584f93.jpg。当https://bgk-photo.cdn.bcebos.com/1f178a82b9014a90041d71dcb9773912b31beeb4.jpg平时时，https://bgk-photo.cdn.bcebos.com/3812b31bb051f8197f06342bcab44aed2e73e7b4.jpg且https://bgk-photo.cdn.bcebos.com/4bed2e738bd4b31c871ea3da97d6277f9e2ff8b4.jpg；相交时，https://bgk-photo.cdn.bcebos.com/fc1f4134970a304e8119979bc1c8a786c9175c93.jpg；垂直时，https://bgk-photo.cdn.bcebos.com/d0c8a786c9177f3ecd0fcb6c60cf3bc79f3d5693.jpg注意：利用斜率判断直线的平行与垂直时，要注意斜率的存在与否。