Precalculus Examples

$\sin (390 + 120)$

Step 1

Add $390$ and $120$ .

$\sin (510)$

Step 2

Remove full rotations of $360$ ° until the angle is between $0$ ° and $360$ °.

$\sin (150)$

Step 3

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

$\sin (30)$

Step 4

The exact value of $\sin (30)$ is $\frac{1}{2}$ .

$\frac{1}{2}$

Step 5

The result can be shown in multiple forms.

Exact Form:

$\frac{1}{2}$

Decimal Form:

$0.5$