Trigonometry Examples

{cos}^{2} (\frac{π}{11}) - {sin}^{2} (\frac{π}{11})

$\cos^{2} (\frac{π}{11}) - \sin^{2} (\frac{π}{11})$

Step 1

Apply the cosine double-angle identity.

cos (2 \frac{π}{11})

$\cos (2 \frac{π}{11})$

Step 2

Combine

2

$2$ and

\frac{π}{11}

$\frac{π}{11}$ .

cos (\frac{2 π}{11})

$\cos (\frac{2 π}{11})$

Step 3

The result can be shown in multiple forms.

Exact Form:

cos (\frac{2 π}{11})

$\cos (\frac{2 π}{11})$

Decimal Form:

0.84125353 \dots

$0.84125353 \dots$