来自秦小丽的问题
求证:tan2x+1tan2x=2(3+cos4x)1−cos4x.
求证:tan2x+1tan2x=2(3+cos4x)1−cos4x.
1回答
2020-05-10 23:20
求证:tan2x+1tan2x=2(3+cos4x)1−cos4x.
求证:tan2x+1tan2x=2(3+cos4x)1−cos4x.
证明:左边=sin2xcos2x+cos2xsin2x=sin4x+cos4xsin2xcos2x=(sin2x+cos2x)2−2sin2xcos2x14sin22x=8−4sin22x1−cos4x=4+4cos22x1−cos4x=4+2(1+cos4x)1−cos4x=2(3+cos4x)1−cos4x=右边.∴tan2x+1tan2x=2(3+cos4x)1...