Trigonometry Examples

$\cos (270 °)$

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 third quadrant.

$- \cos (90)$

Step 2

The exact value of

$\cos (90)$ is

$0$ .

$- 0$

Step 3

Multiply

$- 1$ by

$0$ .

$0$

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