Evaluate cos(pi/4)-cos(pi/4)

$\cos (\frac{π}{4}) - \cos (\frac{π}{4})$

Simplify each term.

The exact value of $\cos (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$\frac{\sqrt{2}}{2} - \cos (\frac{π}{4})$

The exact value of $\cos (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

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

Simplify terms.

Combine the numerators over the common denominator.

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

Subtract $\sqrt{2}$ from $\sqrt{2}$ .

$\frac{0}{2}$

Divide $0$ by $2$ .

$0$