Precalculus Examples

$- \sin (0 - \frac{π}{4})$

Step 1

Subtract $\frac{π}{4}$ from $0$ .

$- \sin (- \frac{π}{4})$

Step 2

Add full rotations of $2 π$ until the angle is greater than or equal to $0$ and less than $2 π$ .

$- \sin (\frac{7 π}{4})$

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 fourth quadrant.

$- - \sin (\frac{π}{4})$

Step 4

The exact value of $\sin (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$- - \frac{\sqrt{2}}{2}$

Step 5

Multiply $- - \frac{\sqrt{2}}{2}$ .

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Step 5.1

Multiply $- 1$ by $- 1$ .

$1 \frac{\sqrt{2}}{2}$

Step 5.2

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

$\frac{\sqrt{2}}{2}$

Step 6

The result can be shown in multiple forms.

Exact Form:

$\frac{\sqrt{2}}{2}$

Decimal Form:

$0.70710678 \dots$