证明sinA+sin(A+2π/3)+sin(A-2π/3)=0
证明sinA+sin(A+2π/3)+sin(A-2π/3)=0
证明(sinA)^2+[sin(A+2π/3)]^2+[sin(A-2π/3)]^2=3/2
1- sin(2π/3 - a)/sina
证明:[sin(a-60)]^2+[sina]^2+[sin(a+60)]^2=3/2
sina(cosa)^3=1/4sin 2a+1/8sin 4a证明过程
sin(3π-a)=sina?
若sinA+cosA/sinA-cosA=2,则sin(A-5π)*sin(3π/2-A)等于?
已知sina-2cosa=0求sin(π-a)cos(2π-a)sin(-a+2分之3π)除以tan(-a-π)sin(
已知sina/cosa=-2,则sin(a-3π)+cos(π-a)/sin(-a)-cos(π+a)
已知sina=15/17,a∈(π/2,π),求sin(π/3+a),sin(π/3-a)
已知sina=15/17,a∈(π/2,π)求sin(π/3+a),sin(π/3-a)
sinb/sina=cos(a+b),证明3sinb=sin(2a+b)