已知sin(A-B)cosA-cos(A-B)sinA=3/5,cos2B=?
已知sin(a-b)cosa-cos(a-b)sina=3/5,那么cos2b的值是多少
已知 A+B+C=π,sinA+sinB+sinC=cosA+cosB+cosC.求 ( cos2A+cos2B+cos
已知sinA=3/5 cosA=3/5 cos(A+B)=12/13 求sin(A+B)
1,已知sin(a-b)cosa-cos(b-a)sina=3/5,b是第三象限角,求sin(b+5pi/4)的值
已知Sin(a-b)Cosa-Cos(B-a)Sina=3/5,B是第三象限Sin(B-5排/4)得
已知SINA+SINB=3/5,COSA+COSB=4/5,求COS(A-B),SIN(A+B)+COS(A+B)
已知AB都是锐角,sin(A-B)=3/5 cos(A+B)=5/13 求COS2B的值.
cosb=cos[(a+b)-a]=cos(a+b)cosa+sin(a+b)sina
化简:sin(a-B)cosa-1/2[sin(2a+B)-sinB]=?已知cos(a-π/6)+sina=4√3/5
sin(a-B)cosa-1/2[sin(2a+B)-sinB]=?已知cos(a-π/6)+sina=4√3/5则si
已知cosa-cosb=1/2,sina-sinb=-1/3,求cos(a-b),sin(a+b)
已知sina+sinB=-2/3,cosa-cosB=1/3.求cos(a+B),sin(a+B)