Precalculus Examples

$\cos (\frac{20 π}{9})$

Step 1

Subtract full rotations of $2 π$ until the angle is greater than or equal to $0$ and less than $2 π$ .

$\cos (\frac{2 π}{9})$

Step 2

The result can be shown in multiple forms.

Exact Form:

$\cos (\frac{2 π}{9})$

Decimal Form:

$0.76604444 \dots$