Trigonometry
Is the given equation an identity?
tan(x−y)+2tan(y−x)=tany−tanx1+tanxtany\tan\left(x-y\right)+2\tan\left(y-x\right)=\frac{\tan y-\tan x}{1+\tan x\tan y}tan(x−y)+2tan(y−x)=1+tanxtanytany−tanx
Yes
No