Precalculus Examples

$\arccos (\tan (- \frac{π}{4}))$

Step 1

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

$\arccos (\tan (\frac{7 π}{4}))$

Step 2

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

$\arccos (- \tan (\frac{π}{4}))$

Step 3

The exact value of $\tan (\frac{π}{4})$ is $1$ .

$\arccos (- 1 \cdot 1)$

Step 4

Multiply $- 1$ by $1$ .

$\arccos (- 1)$

Step 5

The exact value of $\arccos (- 1)$ is $π$ .

$π$

Step 6

The result can be shown in multiple forms.

Exact Form:

$π$

Decimal Form:

$3.14159265 \dots$