1.若x=π/2,则cos^2x-sin^2x的值等于( )A.1/4 B.1/2 C.√2/2 D.√3/22.已知tanx=3/4,则tan2x=( )A.-7/24 B.7/24 C/-24/7 D.24/73.cos75°sin75°的值为( )A.1/4 B.1/2 C√2/2 D.√3/24.已知sin2θ=12/13,π
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![1.若x=π/2,则cos^2x-sin^2x的值等于( )A.1/4 B.1/2 C.√2/2 D.√3/22.已知tanx=3/4,则tan2x=( )A.-7/24 B.7/24 C/-24/7 D.24/73.cos75°sin75°的值为( )A.1/4 B.1/2 C√2/2 D.√3/24.已知sin2θ=12/13,π](/uploads/image/z/7265211-51-1.jpg?t=1.%E8%8B%A5x%3D%CF%80%2F2%2C%E5%88%99cos%5E2x-sin%5E2x%E7%9A%84%E5%80%BC%E7%AD%89%E4%BA%8E%28+%29A.1%2F4+B.1%2F2+C.%E2%88%9A2%2F2+D.%E2%88%9A3%2F22.%E5%B7%B2%E7%9F%A5tanx%3D3%2F4%2C%E5%88%99tan2x%3D%28+%29A.-7%2F24+B.7%2F24+C%2F-24%2F7+D.24%2F73.cos75%C2%B0sin75%C2%B0%E7%9A%84%E5%80%BC%E4%B8%BA%28+%29A.1%2F4+B.1%2F2+C%E2%88%9A2%2F2+D.%E2%88%9A3%2F24.%E5%B7%B2%E7%9F%A5sin2%CE%B8%3D12%2F13%2C%CF%80)
1.若x=π/2,则cos^2x-sin^2x的值等于( )A.1/4 B.1/2 C.√2/2 D.√3/22.已知tanx=3/4,则tan2x=( )A.-7/24 B.7/24 C/-24/7 D.24/73.cos75°sin75°的值为( )A.1/4 B.1/2 C√2/2 D.√3/24.已知sin2θ=12/13,π
1.若x=π/2,则cos^2x-sin^2x的值等于( )
A.1/4 B.1/2 C.√2/2 D.√3/2
2.已知tanx=3/4,则tan2x=( )
A.-7/24 B.7/24 C/-24/7 D.24/7
3.cos75°sin75°的值为( )
A.1/4 B.1/2 C√2/2 D.√3/2
4.已知sin2θ=12/13,π
1.若x=π/2,则cos^2x-sin^2x的值等于( )A.1/4 B.1/2 C.√2/2 D.√3/22.已知tanx=3/4,则tan2x=( )A.-7/24 B.7/24 C/-24/7 D.24/73.cos75°sin75°的值为( )A.1/4 B.1/2 C√2/2 D.√3/24.已知sin2θ=12/13,π
cos^2x-sin^2x=cos2x=-1
第一题无答案
2.D
3.A
4.
sin2θ=12/13,π<θ<5π/4,则cos2θ=5/13
sin4θ=2sin2θcos2θ=120/169
cos4θ=(cos2θ)^2-(sin2θ)^2=-119/169
tan4θ=sin4θ/cos4θ=-120/119
5.D
悬赏太低了