Calculus Examples

$\cos (\frac{- 9 π}{2})$

Step 1

Move the negative in front of the fraction.

$\cos (- \frac{9 π}{2})$

Step 2

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

$\cos (\frac{3 π}{2})$

Step 3

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

$\cos (\frac{π}{2})$

Step 4

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

$0$