讨论x为何值时,等式(2(sin2x+1))/(1+sin2x+cos2x)=tanx+1成立那位数学高手帮帮忙

Question

讨论x为何值时,等式 (2(sin2x+1))/(1+sin2x+cos2x)=tanx+1 成立
那位数学高手帮帮忙

Answer 1

2(sin2x+1)/(cos2x+sin2x+1)=(sinx+cosx)/cosx
=(sinxcosx+cos^2x)/cos^2x=(sin2x+cos2x+1)(cos2x+1)
交叉相乘得：
(sin2x+cos2x+1)^2=2(sin2x+1)(cos2x+1)
展开整理得sin^22x+cos^22x=1
恒等式?