化简:{cos(4a-兀/2)乘以 sin(兀/2-a) 乘以 cos2a } / { (1+cos2a) 乘以 (1+
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化简:{cos(4a-兀/2)乘以 sin(兀/2-a) 乘以 cos2a } / { (1+cos2a) 乘以 (1+cos4a)乘以cosa}
![化简:{cos(4a-兀/2)乘以 sin(兀/2-a) 乘以 cos2a } / { (1+cos2a) 乘以 (1+](/uploads/image/z/17864206-70-6.jpg?t=%E5%8C%96%E7%AE%80%EF%BC%9A%7Bcos%EF%BC%884a-%E5%85%80%2F2%EF%BC%89%E4%B9%98%E4%BB%A5+sin%28%E5%85%80%2F2-a%29+%E4%B9%98%E4%BB%A5+cos2a+%7D+%2F+%7B+%281%2Bcos2a%29+%E4%B9%98%E4%BB%A5+%EF%BC%881%2B)
cosx是偶函数
cos(4a-π/2)=cos(π/2-4a)=sin(4a)=2sin2acos2a
sin(π/2-a)=cosa
1+cos2a=2cos²a-1+1=2cos²a
1+cos4a=2cos²2a-1+1=2cos²2a
原式
=(2sin2acos2a*cosa*cos2a)/(2cos²a*2cos²2a*cosa)
=(sin2a)/(2cos²a)
=(2sinacosa)/(2cos²a)
=tana
cos(4a-π/2)=cos(π/2-4a)=sin(4a)=2sin2acos2a
sin(π/2-a)=cosa
1+cos2a=2cos²a-1+1=2cos²a
1+cos4a=2cos²2a-1+1=2cos²2a
原式
=(2sin2acos2a*cosa*cos2a)/(2cos²a*2cos²2a*cosa)
=(sin2a)/(2cos²a)
=(2sinacosa)/(2cos²a)
=tana
化简[cos(4a-π/2)*sin(π/2-a)*cos2a]/[(1+cos2a)(1+cos4a)*cosa
化简[2sin2a/(1+cos2a)]*(cos^2a/cos2a)
已知sin a+cos a=1/3,a属于(π/2,π),求cos2a
cos2a-1+2sin^2a
三角比:[cos(4a-PAI/2)*sin(PAI/2-2a)]/[(1+cos2a)*(1+cos4a)]
求证:sin a (1+cos2a)=sin a cos a
化简sin^2(a)*sin^2(b)+cos^2(a)*cos^2(b)-1/2cos2a*cos2b
sin^2a乘以tana+cos^2a乘以cota+2sina乘以cosa-cota
化简 cos2a/(1-2tana*cos^2a)
cos2A+cos(4π/3-2A)化简,
已知cos2a=(1/4),求cos^4a+sin^4+sin^2acos^2a的值
化简sin^4a-cos^4a/cos2a