Question

一些简单的。美高的数学。。

不做的话翻译给我也行啊T T

Answer 1

(1) since α is in the first quadrant s.t. sinα=1/3
so cosα=2√2/3
since β is in the fourth quadrant s.t. cosβ=3/4
so sinβ=-√7/4
thus cos(α -β)=cosαcosβ-sinαsinβ=(6√2+√7)/12
(2)sorry I dont know how to factorize it
(这题是要你求f(x)=0的根并保留一位小数，我能想到的是对他因式分解后求，但我不会分
如果可以用计算机的话我会用牛顿迭代法去求，但很难想象这是高中生的习题)

(3)the cross product of these two vectors is (8,-7,-9)
(4)according to the law of cosines, c2=a2+b2-2abcosc, so c=10√21
(5)move 1 unit to right along the x axis