Trigonometry Examples

$\sin (x) = \tan (x) \cos (x)$

Step 1

Start on the right side.

$\tan (x) \cos (x)$

Step 2

Write $\tan (x)$ in sines and cosines using the quotient identity.

$\frac{\sin (x)}{\cos (x)} \cos (x)$

Step 3

Cancel the common factor of $\cos (x)$ .

$\sin (x)$

Step 4

Because the two sides have been shown to be equivalent, the equation is an identity.

$\sin (x) = \tan (x) \cos (x)$ is an identity