Trigonometry Examples

$\sin (\frac{3 π}{2} + x)$

Step 1

Apply the sum of angles identity.

$\sin (\frac{3 π}{2}) \cos (x) + \cos (\frac{3 π}{2}) \sin (x)$

Step 2

Simplify terms.

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Step 2.1

Simplify each term.

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Step 2.1.1

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.

$- \sin (\frac{π}{2}) \cos (x) + \cos (\frac{3 π}{2}) \sin (x)$

Step 2.1.2

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

$- 1 \cdot 1 \cos (x) + \cos (\frac{3 π}{2}) \sin (x)$

Step 2.1.3

Multiply $- 1$ by $1$ .

$- 1 \cos (x) + \cos (\frac{3 π}{2}) \sin (x)$

Step 2.1.4

Rewrite $- 1 \cos (x)$ as $- \cos (x)$ .

$- \cos (x) + \cos (\frac{3 π}{2}) \sin (x)$

Step 2.1.5

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

$- \cos (x) + \cos (\frac{π}{2}) \sin (x)$

Step 2.1.6

The exact value of $\cos (\frac{π}{2})$ is $0$ .

$- \cos (x) + 0 \sin (x)$

Step 2.1.7

Multiply $0$ by $\sin (x)$ .

$- \cos (x) + 0$

Step 2.2

Add $- \cos (x)$ and $0$ .

$- \cos (x)$