Simplification of trigonometric function Tan (tan-1 (8 / 6) / 2) Tan-1 means arc tan That is to say, Tan times 1 / 2 (arc tan4 / 3) How to simplify, teach me five Sorry, 0.5 was pressed by my computer

Arc tan4 / 3 shows that Tan a = 4 / 3, Sina = 4 / 5, cosa = 3 / 5
tan(A/2)=(sinA)/(1+cosA)=(4/5)/[1+(3/5)]=4/8=0.5
How do I feel there is an answer?
If Tan a = 4 / 3, Sina = - 4 / 5, cosa = - 3 / 5 can be deduced
So the result is Tan (A / 2) = - 2. Is there any other condition?

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