若tan2次方α=1/2,求cos2α=?sin2α=?
来源:学生作业帮助网 编辑:作业帮 时间:2024/06/25 17:27:10
![若tan2次方α=1/2,求cos2α=?sin2α=?](/uploads/image/z/1017237-21-7.jpg?t=%E8%8B%A5tan2%E6%AC%A1%E6%96%B9%CE%B1%3D1%2F2%2C%E6%B1%82cos2%CE%B1%3D%3Fsin2%CE%B1%3D%3F)
若tan2次方α=1/2,求cos2α=?sin2α=?
若tan2次方α=1/2,求cos2α=?sin2α=?
若tan2次方α=1/2,求cos2α=?sin2α=?
sin2α=2√2/3 cos2α=1/3
题目都没没有表达清楚,叫人怎么做??
(tanα)^2=1/2
tanα = 1/√2 or -1/√2
cos2α = 2(cosα)^2 -1
= 2(√2/3)^2 -1
= 4/9 - 1
= -5/9
(sin2α)^2 = 1-(cos2α)^2
= 1- 25/81
= 56/81
sin2α = 2√14/9 or -2√14/9