几道数学简单的2倍角函数题
(1)tana-1/tana=-2/tan2a
(2)tan(a+pai/4)+tan(a-pai/4)=2tan2a
(3)1+sin2a/sina+cosa=sina+cosa
(4)sina(1+cos2a)=sin2acosa
(5)2sin(pai/4+a)sin(pai/4-a)=cos2a
(6)1+sin2a-cos2a/1+sin2a+cos2a=tana