求证 2sin(π+a)cos(π-a)-sin2a
若2sin(π/4+a)=sinθ+cosθ,2sin^2β=sin2θ,求证sin2a+(1/2)cos2β=0.
若2sin(π/4+a)=sinθ+cosθ,2sin^2β=sin2θ,求证sin2a+(1/2)cos2β=0
1-sin2a-cos^2(a-π/4)
已知tan(π+a)=-1/3求[sin(π-2a)+cos^2a]/[2cos2a+sin2a+2]
求证 cos(A)+ 根号3sin(A)=2sin(π/6+A)
2sin(π/4+a)=sinθ+cosθ,且2sin^2b=sin2θ,求sin2a+1/2cos2b
已知tan(a+π/4)=-1/2,π/2<a<π,求(sin2a-2cos^2a)/√2sin(a-π/4
已知tan(a+4/π)=1/2 ,且-π/2<a<0,则(2sin^2a+sin2a)/cos(a-4/π)=
已知cos(a+π/4)=3/5,17π<a<7π/4,求sin2a+2sin^2a/1-tana的值
已知π/2<B<A<3π/4,cos(A-B)=12/13,sin(A+B)=-3/5,求sin2A
求证:cos^2a/[cot(a/2)-tan (a/2)]=1/4sin2a
已知sin(3π+a)=2sin[(3π/2)+a],求sin^2a+sin2a的值