Trigonometry Examples

$\cos (90 + 240)$

Step 1

Add $90$ and $240$ .

$\cos (330)$

Step 2

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.

$\cos (30)$

Step 3

The exact value of $\cos (30)$ is $\frac{\sqrt{3}}{2}$ .

$\frac{\sqrt{3}}{2}$

Step 4

The result can be shown in multiple forms.

Exact Form:

$\frac{\sqrt{3}}{2}$

Decimal Form:

$0.86602540 \dots$