Cos x / tan x + sec x – cos x / tan x – sec x =…

{cos x / (tan x + sec x)} – {cos x / (tan x – sec x)}
perhatikan
a/b – a/c = (ac – ab)/bc
jadi
{cos x(tan x – sec x) – cos x(tan x + sec x)}
————————————————————
(tan x + sec x) (tan x – sec x)

cos x{(tan x – sec x) – (tan x + sec x)}
—————————————————–
tan²x – sec²x

cos x(tan x – sec x – tan x – sec x)
————————————————
tan²x – sec²x

cos x(-2.sec x)
———————-
tan²x – sec²x

cos x(-2/cos x)
———————
tan²x – sec²x

-2/-1
= 2