Answer
$\dfrac{\tan x}{\sec x}=\sin x$
Work Step by Step
$\dfrac{\tan x}{\sec x}=\sin x$
Substitute $\tan x$ with $\dfrac{\sin x}{\cos x}$ and $\sec x$ with $\dfrac{1}{\cos x}$. Then simplify:
$\dfrac{\Big(\dfrac{\sin x}{\cos x}\Big)}{\Big(\dfrac{1}{\cos x}\Big)}=\sin x$
Take away the cosines and the identity is proved
$\sin x=\sin x$
