向量的主要性质①向量的加法适合向量加法的三角形法则或平行四边形法则,即AB+BC=AC; ②若e1、e2是平面α内非零不共线向量,则对于α内任一向量a,有且只有一对实数λ1λ2,使得a=λ1 e1+λ2 e2成立; ③非零向量a=(x1,y1),b=(x2,y2)的数量积为a·b=x1x2+y1y2; ④设非零向量a=(x1,y1),b=(x2,y2),则a⊥b(?)a·b=x1x2+y1y2=0; The main property of the vector 1 Addition of vectors Fit the triangle rule or parallelogram rule of the vector addition, ie AB+BC=AC; 2 If e1, e2 is a non-zero non-collinear vector in the plane α, then for any vector within α , There is only one pair of real numbers λ1λ2, such that a=λ1 e1+λ2 e2 holds; 3 The non-zero vector a=(x1,y1), b=(x2,y2) is the product of a·b=x1x2+y1y2; 4 Let a non-zero vector a=(x1,y1) b=(x2,y2), then a⊥b(?)a·b=x1x2+y1y2=0;