在高中数学教材中,向量数量积的坐标形式是通过数量积性质得到的.本文意在通过数量积的定义直接得到坐标形式,使学生学习起来有一种一气呵成之感.已知:a=(x_1,y_1),b=(x_2,y_2),求证:a·b=x_1x_2+y_1y_2证明令a=OA,b=OB,则A,B两点的坐标分别为(x_1,Y_1)和(x_2,y_2),OA,OB分别在α和β终边上,且θ=〈a,b〉= In high school mathematics teaching materials, the coordinate form of vector quantity product is obtained by the property of quantity and quantity.This paper intends to get the coordinate form directly by the definition of quantity product, so that students can learn to have a coherent feeling.It is known that: a = (x_1 (x_1, y_1) and (x_2, y_2), b = (x_2, y_2), and verify that: a · b = x_1x_2 + y_1y_2, we prove that a = OA and b = y 2), OA, OB are respectively on the end of α and β, and θ = =