化简 cos(a-b)cos(a+b)+sin(a-b)sin(a+b).

化简COS(a+B)COS(a-B)+sin平方B 化简cos(a+b)cos(a-b)+sin^2b 化简：2cos(A+B)cosB-cos(2A+B) COS(a-B)公式 证明cos(A+B) cos a-cos b 公式是什么? 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^2acos^b-cos^2asin^2b+cos^a-cos^2b 化简 cos(a+b)cosa+sin(a+b)sina=_______ cos(31°-a)cos(29°+a)-cos(59°+a)cos(61°-a) 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,sin(a+b)cos(r-b)-cos(b+a)sin(b-r) 化简 ：sin(a+b)cos(r-b)-cos(b+a)sin(b-r) sin(a-b)sin(b-r)-cos(a-b)cos(r-b)sin(a+b)cos(r-b)-cos(b+a)sin(b-r) 和 sin(a-b)sin(b-r)-cos(a-b)cos(r-b) 证明：cos(a+b)*cos(a-b)=cos2b-cos2a 如何证明|cos a-cos b | ≤| a - b 帮我证明|cos a-cos b | ≤| a - b |