Trigonometry Examples

$\cos (180) - \sin (180)$

Step 1

Simplify each term.

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Step 1.1

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.

$- \cos (0) - \sin (180)$

Step 1.2

The exact value of $\cos (0)$ is $1$ .

$- 1 \cdot 1 - \sin (180)$

Step 1.3

Multiply $- 1$ by $1$ .

$- 1 - \sin (180)$

Step 1.4

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

$- 1 - \sin (0)$

Step 1.5

The exact value of $\sin (0)$ is $0$ .

$- 1 - 0$

Step 1.6

Multiply $- 1$ by $0$ .

$- 1 + 0$

Step 2

Add $- 1$ and $0$ .

$- 1$