tan(π/4+x/2) =
(tan π/4 + tan x/2)
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1 - tan π/4 tan x/2
(1+tan(x/2))/(1-tan(x-2))
see where this takes you, and recall the half-angle formula for tan(x/2)
prove that tan(π/4+x/2)+tan(π/4-x/2)=2sec x
1 answer