Trigonometry Examples

$1 - 2 \sin^{2} (\frac{3 π}{5})$

Step 1

Apply the cosine double-angle identity.

$\cos (2 \frac{3 π}{5})$

Step 2

Multiply $2 \frac{3 π}{5}$ .

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Step 2.1

Combine $2$ and $\frac{3 π}{5}$ .

$\cos (\frac{2 (3 π)}{5})$

Step 2.2

Multiply $3$ by $2$ .

$\cos (\frac{6 π}{5})$

$\cos (\frac{6 π}{5})$

Step 3

The result can be shown in multiple forms.

Exact Form:

$\cos (\frac{6 π}{5})$

Decimal Form:

$- 0.80901699 \dots$

$[\begin{array}{c} x^{2} & \frac{1}{2} \\ \sqrt{π} & \int x d x \end{array}]$