已知cos(π +α)=3/50,则tan(2π-α)的值是

题目

已知cos(π +α)=3/50,则tan(2π-α)的值是

答案

sinα=√5/5
α为锐角 则cosα>0
(cosα)^2+(sinα)^2=1
cosα=2√5/5
sinβ=√10/10
α为锐角 则cosβ>0
(cosβ)^2+(sinβ)^2=1
cosβ=3√10/10
sin(α+β)=sinαcosβ+cosαsinβ
=√5/5*3√10/10+2√5/5*√10/10
=(5√50)/50
=5/√50
=5/(5√2)
=√2/2
α、β都是区间(0,π/6)的角
0<α+β<π/6*3=π/3
所以α+β= π/4
你的串号我已经记下,采纳后我会帮你制作