sin(a+b)cosa-cos(a+b)sina=5/13 则sin（π-B)=?

若cos(a+B)*cosa+sin(a+B)*sina=-4/5,则sin(π/2-B) a,b为锐角 且cos(a+b)=sin(a-b),则sina-cosa= cosb=cos[(a+b)-a]=cos(a+b)cosa+sin(a+b)sina sin(a-b)cosa-cos(a-b)sina=3/5,b在第三象限,则cosb/2为多少 sin(a-B)cosa-1/2[sin(2a+B)-sinB]=?已知cos(a-π/6)+sina=4√3/5则si 已知sinA=3/5 cosA=3/5 cos(A+B)=12/13 求sin(A+B) 常用结论,SinA±CosA=t则SinA平方,sinA平方-cosA平方,sin三方A±cos三方B,sin四方A—c 证明下列恒等式：sin(a+b)*cos(a-b）=sina*cosa+sinb*cosb 若cos(a-b)cosa+sin(a-b)sina=-4/5,且b是第三象限角,则cos(b/2)的值为 化简 cos(a+b)cosa+sin(a+b)sina=_______ cos(31°-a)cos(29°+a)-co 化简：sin(a-B)cosa-1/2[sin(2a+B)-sinB]=?已知cos(a-π/6)+sina=4√3/5 求证： sina+sinb=2sin[(a+b)/2]cos[(a-b)/2] cosa+cosb=2cos[(a+b)