1:0.5;
2:一;
3:2,90°
4:0.75;
5:【π/6,2π/3】
6:【π/6+2kπ,5π/6+2kπ】,k∈Z
7:16/6
8:【1/4,1/2】
9:相交
10:2
后面的再补上
11:cosα
12:(-无穷大,0)
13:x=2和5x-12y+26=0
14:cos(α-105)=cos(75°+α-180°)=-cos(α+75°)=-1/3;
cos(105-α)=-1/3;
105-α在第二象限,所以sin(105-α)=三分之二倍根号2
结果就等于:三分之二倍根号-1/3