Trigonometry Examples

$5 \cos (2 \cdot 240)$

Step 1

Multiply $2$ by $240$ .

$5 \cos (480)$

Step 2

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

$5 \cos (120)$

Step 3

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.

$5 (- \cos (60))$

Step 4

The exact value of $\cos (60)$ is $\frac{1}{2}$ .

$5 (- \frac{1}{2})$

Step 5

Multiply $5 (- \frac{1}{2})$ .

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Step 5.1

Multiply $- 1$ by $5$ .

$- 5 (\frac{1}{2})$

Step 5.2

Combine $- 5$ and $\frac{1}{2}$ .

$\frac{- 5}{2}$

Step 6

Move the negative in front of the fraction.

$- \frac{5}{2}$

Step 7

The result can be shown in multiple forms.

Exact Form:

$- \frac{5}{2}$

Decimal Form:

$- 2.5$

Mixed Number Form:

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