作业帮证明cos^2(A+B)—sin^2(A—B)=cos2Acos2B
来源：学生作业帮 编辑：作业帮 分类：综合作业 时间：2024/05/10 19:48:25
证明cos^2(A+B)—sin^2(A—B)=cos2Acos2B
cos^2(A+B)-sin^2(A-B)=[cos(A+B)+sin(A-B)][cos(A+B)-sin(A-B)]=(cosAcosB-sinAsinB+sinAcosB-cosAsinB)(cosAcosB-sinAsinB-sinAcosB+cosAsinB)=(cosA)^2(cosB)^2-sinAsinBcosAcosB-(cosB)^2sinAcosA+(cosA)^2sinBcosB-sinAsinBcosAcosB+(sinA)^2(sinB)^2+(sinA)^2sinBcosB-(sinB)^2sinAcosA+(cosB)^2sinAcosA-(sinA)^2sinBcosB-(sinA)^2(cosB)^2+sinAcosAsinBcosB-(cosA)^2sinBcosB+(sinB)^2sinAcosA+sinAsinBcosAcosB-(cosA)^2(sinB)^2=(cosA)^2(cosB)^2+(sinA)^2(sinB)^2-(sinA)^2(cosB)^2-(cosA)^2(sinB)^2=[(cosA)^2-(sinA)^2][(cosB)^2-(sinB)^2]=cos2Acos2B
证明cos^2(A+B)—sin^2(A—B)=cos2Acos2B
证明cos²（A+B）—sin²（A—B）=cos2Acos2B
证明 cos的平方2(A+B)-sin的平方2(A-B)=cos2Acos2B
若sin^4a/sin^2b+cos^4a/cos^2b=1,证明sin^4b/sin^2a+cos^4b/cos^2a
证明三角函数等式sin(A+B)-sinA=2cos(A+B/2)sin(B/2)
cos(a+b)=cos(a)*cos(b)-sin(a)*sin(b) 用三角形证明
证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2
如何证明sinA+sinB=2sin((A+B)/2)cos((A-B)/2)
证明sin(2a+b)/sina-2cos(a+b)=sinb/sina
sinb/sina=cos(a+b),证明3sinb=sin(2a+b)
证明2sin(a+b)cos(a-b)=sin2a+sin2b
已知tanA,tanB是方程X^2－4PX-3=0的两个根,求2COS2ACOS2B+2sin^2（A-B）