Precalculus Examples

$2 \sin (- \frac{3}{5}) \cos (\frac{4}{5})$

Step 1

Since $\sin (- \frac{3}{5})$ is an odd function, rewrite $\sin (- \frac{3}{5})$ as $- \sin (\frac{3}{5})$ .

$2 (- \sin (\frac{3}{5})) \cos (\frac{4}{5})$

Step 2

Multiply $- 1$ by $2$ .

$- 2 \sin (\frac{3}{5}) \cos (\frac{4}{5})$

Step 3

The result can be shown in multiple forms.

Exact Form:

$- 2 \sin (\frac{3}{5}) \cos (\frac{4}{5})$

Decimal Form:

$- 0.78678039 \dots$