化简cos(a+b)cos(a-b)+sin^2b

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化简cos(a+b)cos(a-b)+sin^2b
化简cos(a+b)cos(a-b)+sin^2b

化简cos(a+b)cos(a-b)+sin^2b
cos(a+b)cos(a-b)+sin^2b
=(cosacosb-sinasinb)(cosacosb+sinasinb)+sin^2b
=cos^2acos^2b-sin^2asin^2b+sin^2b
=cos^2acos^2b+cos^2asin^2b
=cos^2a

原式=1/2(cos2a+cos2b)+1/2(1-cos2b)
=1/2cos2a+1/2
=cos^2a
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sin（a B)sin(B-y)-cos(a B)cos(y-B) =sin（a B)sin(B-y)-cos(a B)cos(B-y) =-cos(a B B-y) =-cos(a 2B-y) 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 |