论文部分内容阅读
数量积的运算结果是实数,所以求数量积的关键在于其向实数转化的过程.下面就谈谈数量积实数化的常见途径.1.利用数量积的定义例1若|a|=5,|b|=4,a和b的夹角为120°,贝a·b的值是______.解根据数量积定义,得a·b=|a||b|cosθ=5×4×(-(1/2))=-10.注利用定义将数量积实数化是最基本的方法,关键是找到两向量的模与夹角.
The product of the number of products is a real number, so the key to finding the product of the number is the process of its conversion to real numbers. Now let’s talk about the common way to the number of real product .1 Definition of the use of the number of products Example 1 If | a | = 5, | b | = 4, the angle between a and b is 120 °, and the value of b a · b is ______. The solution is defined according to the quantity product, and a · b = | a || b | cos θ = 5 × 4 × - (1/2)) = - 10. Note It is the most basic method to use the definition to real number quantity product. The key is to find the mode and angle between two vectors.