Trigonometry Examples

$\cos (\frac{11 π}{18}) \cos (\frac{2 π}{9}) - \sin (\frac{11 π}{18}) \sin (\frac{2 π}{9})$

Step 1

The result can be shown in multiple forms.

Exact Form:

$\cos (\frac{11 π}{18}) \cos (\frac{2 π}{9}) - \sin (\frac{11 π}{18}) \sin (\frac{2 π}{9})$

Decimal Form:

$- 0.86602540 \dots$