Find the Exact Value cos(390 degrees )

$\cos (390 °)$

Remove full rotations of $360$ ° until the angle is between $0$ ° and $360$ °.

$\cos (30)$

The exact value of $\cos (30)$ is $\frac{\sqrt{3}}{2}$ .

$\frac{\sqrt{3}}{2}$

The result can be shown in multiple forms.

Exact Form:

$\frac{\sqrt{3}}{2}$

Decimal Form:

$0.86602540 \dots$