f(x)= tanx/secx

Question

Tell whether or not f(x)=sinx is an identity

Answer 1

tan x = sin x / cos x

sec x = 1 / cos x

 

So...

 

tan x / sec x =

(sin x / cos x) / (1 / cos x) =

(sin x / cos x) * cos x =

sin x

 

So yes, it is an identity.