Precalculus Examples

$\cos^{2} (\frac{π}{13}) - \sin^{2} (\frac{π}{13})$

Step 1

Apply the cosine double-angle identity.

$\cos (2 \frac{π}{13})$

Step 2

Combine $2$ and $\frac{π}{13}$ .

$\cos (\frac{2 π}{13})$

Step 3

The result can be shown in multiple forms.

Exact Form:

$\cos (\frac{2 π}{13})$

Decimal Form:

$0.88545602 \dots$