Find the Exact Value cos(405 degrees )

$\cos (405 °)$

Step 1

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

$\cos (45)$

Step 2

The exact value of $\cos (45)$ is $\frac{\sqrt{2}}{2}$ .

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

Step 3

The result can be shown in multiple forms.

Exact Form:

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

Decimal Form:

$0.70710678 \dots$