Question

高一数学求大神！！！！！！

Answer 1

1
tan(8π/3)
=-tan(π/3)
2
AB=(3,-4)
|AB|=5
单位向量=(3/|AB|,-4/|AB|)
=(3/5,-4/5)
3
k=2n-1即k为奇数
{x|2n-(3π/4)<x<2n-(π/2)}
k=2n即k为偶数
{x|2n+(π/4)<x<2n+(π/2)}
4
l=2r

C=2r+2r
=4r
S=lr/2
5
(3/4)*(1/3)-sinαcosα=0
(1/4)-(1/数段2)sin2α=0
sin2α=1/2
α=15°或漏银75°
6
sinα=12/13
cosα=-5/返毕宴13
tanα=-12/5
tan2α=2tanα/(1-tan²α)
=(-24/5)/(-119/25)
=120/119

Answer 2

D A C A D B