sin（a+B)sin(B-y)-cos(a-B)cos(y-B) 化简

sin(a+B)cos(y-B)-cos(B+a)sin(B-y) 化简 sin（a+B)sin(B-y)-cos(a-B)cos(y-B) 化简 化简cos(a-B)cos(a-y)-sin(a-B)sin(y-a) 高二数学,三角函数化简两题sin(a+b)cos(y-b)-cos(b+a)sin(b-y)sin(a-b)sin(b-y)-cos(a-b)cos(y-b) 三角函数的化简问题sin(a+b)cos(y-b)-cos(b+a)sin(b-y)在这里书上的解答是：sin(a+b)cos(b-y)-cos(b+a)sin(b-y)然后再下一步,这里我不懂的是为什么不能是sin(a+b)cos(y-b)-cos(b+a)sin(y-b)cos为什么是正值，这道题上 为什么设y *＝A cos x +B sin x 如何证明sin(a+b)=sin(a)cos(b)+cos(α)sin(b) 化简COS(a+B)COS(a-B)+sin平方B 化简cos(a+b)cos(a-b)+sin^2b sin平方a*cos平方b-cos平方a*sin平方b为什么等于sin平方a-sin平方b? 化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b sin^2a+sin^2b-sin^2a * sin^2b+cos^2a * cos^2b 化简 sin^2 (A)+sin^2(B)-sin^2(A)sin^2(B)+cos^2(A)cos^2(B) 证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1 cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简 化简 cos(a-b)cos(a+b)+sin(a-b)sin(a+b). cos(a-b)cos(a+b)+sin(a-b)sin(a+b)化简, 化简（sin(a-b)-2sin a cos b）/2sin a sin b +coa(a+b)