buktikan tan x / 1 + sec x = sec x - 1 / tan x

tan x : (1 + sec x) = (sec x - 1)/tan x
(sin x / cos x) : (1 + (1/cos x) = (sec x - 1) / tan x
(sin x / cos x) : ((cos x + 1)/cos x) = (sec x - 1) / tan x
(sin x / cos x) x (cos x/(cos x + 1)) = (sec x - 1) / tan x
(sin x / (cos x + 1)) x ((cos x - 1)/(cos x - 1)) = (sec x - 1) / tan x
(sin x (cos x - 1)/(cos² x - 1)) = (sec x - 1) / tan x
(sin x (cos x - 1)/ -sin² x )) = (sec x - 1) / tan x
((1 - cos x)/ sin x )) = (sec x - 1) / tan x
((1 - cos x)/ sin x )) x (cos x/cos x) = (sec x - 1) / tan x (T)
/ ditulis kebawah biar jelas