Trigonometry Examples

$\sin (\frac{- 13 π}{2})$

Step 1

Move the negative in front of the fraction.

$\sin (- \frac{13 π}{2})$

Step 2

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

$\sin (\frac{3 π}{2})$

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.

$- \sin (\frac{π}{2})$

Step 4

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

$- 1 \cdot 1$

Step 5

Multiply $- 1$ by $1$ .

$- 1$