Algebra Examples

\cos (\frac{2 π}{3})

$\cos (\frac{2 π}{3})$

Step 1

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.

- \cos (\frac{π}{3})

$- \cos (\frac{π}{3})$

Step 2

The exact value of

\cos (\frac{π}{3})

$\cos (\frac{π}{3})$ is

\frac{1}{2}

$\frac{1}{2}$ .

- \frac{1}{2}

$- \frac{1}{2}$

Step 3

The result can be shown in multiple forms.

Exact Form:

- \frac{1}{2}

$- \frac{1}{2}$

Decimal Form:

- 0.5

$- 0.5$