平行向量有一个很简单的性质及其推论 ,从它出发 ,可以独辟蹊径而且很简单地解决解析几何中一些经典的或有趣的问题 .方法之妙 ,值得学习 .1　性质及推论性质 1　如果向量a∥n ,n0 是n的单位向量 ,则a =(a·n0 )n0 .证明　∵a∥n0 ,∴a =kn0 (k∈R) ,∴a·n0 =k(n0 ·n0 ) =k , A parallel vector has a very simple nature and its inferences. Starting from it, it is possible to find new and simple solutions to some classical or interesting problems in analytical geometry. The method is good and worth learning. 1 Properties and inference properties 1 If vector a ∥n, n0 is the unit vector of n, then a = (a·n0)n0. Prove that ∵a∥n0, ∴a = kn0 (k∈R), ∴a·n0 = k(n0 ·n0) =k,