Trigonometry Examples

$\cos (\frac{3 π}{5}) \cos (\frac{π}{15}) - \sin (\frac{3 π}{5}) \sin (\frac{π}{15})$

Step 1

The result can be shown in multiple forms.

Exact Form:

$\cos (\frac{3 π}{5}) \cos (\frac{π}{15}) - \sin (\frac{3 π}{5}) \sin (\frac{π}{15})$

Decimal Form:

$- 0.4\overline{9}$