请完成下面4道题(1)sin105°,(2)sin(-15°),(3)sin80°cos20°-cos80°sin20°,(4)sin33°cos27°+cos33°sin27°
举一反三
- 【计算题】已知sinα+cosα=1,求:(1)sinαcosα; (2)sin α-cos α; (3)sin α-cos α
- 【单选题】sin ( α+β ) = A. sinαcosβ-cosαsinβ B. cosαsin β-sin αcos β C. sinαcosβ+cosαsinβ D. cos αcos β-sin α sin β
- sin(α-β)cosβ+cos(α-β)sinβ=( ) A: sin(α-2β) B: cos(α-2β) C: sinα D: cosα
- 【单选题】设y=sin(cos(x)),求 结果为:(本题10.0分) A. cos(cos(x))*cos(x)+ sin(cos(x))*sin(x)^2 B. - cos(cos(x))*cos(x) - sin(cos(x))*sin(x)^2 C. - cos(cos(x))*cos(x)^2 - sin(cos(x))*sin(x)^2 D. - cos(cos(x))*cos(x) ^2- sin(cos(x))*sin(x)
- cos（α-15°）cos（α+15°）+sin（α-15°）sin（α+15°）=______．