Trigonometry Examples

$\sin (330) \sin (270)$

Step 1

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

$- \sin (30) \sin (270)$

Step 2

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

$- \frac{1}{2} \sin (270)$

Step 3

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

$- \frac{1}{2} (- \sin (90))$

Step 4

The exact value of $\sin (90)$ is $1$ .

$- \frac{1}{2} (- 1 \cdot 1)$

Step 5

Multiply $- 1$ by $1$ .

$- \frac{1}{2} \cdot - 1$

Step 6

Multiply $- \frac{1}{2} \cdot - 1$ .

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Step 6.1

Multiply $- 1$ by $- 1$ .

$1 (\frac{1}{2})$

Step 6.2

Multiply $\frac{1}{2}$ by $1$ .

$\frac{1}{2}$

Step 7

The result can be shown in multiple forms.

Exact Form:

$\frac{1}{2}$

Decimal Form:

$0.5$