已知锐角a b y 且 sina+siny=sinb,cosa-cosy=cosb,求a-b的值
已知锐角a b y 且 sina+siny=sinb,cosa-cosy=cosb,求a-b的值
已知锐角abc满足sina-sinb+siny=0,cosa-cosb-cosy=0,求a-b
已知sina+sinb+siny=0,cosa+cosb+cosy=0.(1)求cos(a-b)的值;(2)若a.b.y
.已知sina+sinb+siny=0,cosa+cosb+cosy=0,求cos(b-y)的值.(解题
已知sina+sinb+siny=0,cosa+cosb+cosy=0,求cos(b-y)的值
已知COSa+COSb+COSy=0,SINa+SINb+SINy=0,求COS(b-y)的值
已知sina+sinB+siny=o,cosa+cosB+cosy=o,哪么cos(B-y)的值为多少
sina+sinb+siny=0.cosa+cosb-cosy=0,则cos(a-b)的值是,
已知sina+sinb=siny,cosa+cosb=cosy,求证cos(a-y)=1/2
若sina+sinb+siny=cosa+cosb+cosy=0,则cos(a-b)等于
三角恒等变换1已知sina+sinb+siny=0,cosa+cosb+cosy=0,求cos(b-y)的值
已知:a,b为锐角,且sina-sinb=-1/3,cosa-cosb=1/2,求:tan(a+b)的值.请写出计算过程