单位向量是一类特殊的向量.教科书上定义单位向量是长度等于1个单位长度的向量,其方向随具体问题而定.如果熟练应用单位向量,可以起到事半功倍的效果.例1已知b的方向与a=(-3,4)的方向相同,且|b|=15,求b.分析已知|b|,要求b,只要求b的单位向量(即与b同向的单位向量)就行了,于是联 The unit vector is a special kind of vector. The textbook defines the unit vector as a vector whose length is equal to 1 unit length. Its direction depends on the specific problem. If you are skilled in applying the unit vector, you can achieve a multiplier effect. Example 1 Known b The direction is the same as a=(-3,4), and |b|=15, find b. Analyze the known |b|, request b, only require the unit vector of b (that is, the unit vector in the same direction as b ) On the line, then