Trigonometry Examples

$\cos (x) \cdot \tan (- x)$

Step 1

Since $\tan (- x)$ is an odd function, rewrite $\tan (- x)$ as $- \tan (x)$ .

$\cos (x) \cdot (- \tan (x))$

Step 2

Rewrite in terms of sines and cosines, then cancel the common factors.

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Reorder $\cos (x)$ and $- \tan (x)$ .

$- \tan (x) \cdot \cos (x)$

Add parentheses.

$- (\tan (x) \cdot \cos (x))$

Rewrite $\cos (x) \cdot (- \tan (x))$ in terms of sines and cosines.

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

Cancel the common factors.

$- \sin (x)$