Trigonometry Examples

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

Step 1

The result can be shown in multiple forms.

Exact Form:

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

Decimal Form:

$0.86602540 \dots$