Precalculus Examples

$\arccos (\sin (\frac{3 π}{2}))$

Step 1

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.

$\arccos (- \sin (\frac{π}{2}))$

Step 2

The exact value of $\sin (\frac{π}{2})$ is $1$ .

$\arccos (- 1 \cdot 1)$

Step 3

Multiply $- 1$ by $1$ .

$\arccos (- 1)$

Step 4

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

$π$

Step 5

The result can be shown in multiple forms.

Exact Form:

$π$

Decimal Form:

$3.14159265 \dots$