Find the Exact Value cos(-9pi)

$\cos (- 9 π)$

Find an angle that is coterminal to $- 9 π$ .

Tap for more steps…

Add $2 π$ to $- 9 π$ .

$A = - 9 π + 2 π$

The resulting angle of $- 7 π$ is coterminal with $- 9 π$ but isn’t positive. Repeat the step.

$A = - 7 π$

Add $2 π$ to $- 7 π$ .

$A = - 7 π + 2 π$

The resulting angle of $- 5 π$ is coterminal with $- 9 π$ but isn’t positive. Repeat the step.

$A = - 5 π$

Add $2 π$ to $- 5 π$ .

$A = - 5 π + 2 π$

The resulting angle of $- 3 π$ is coterminal with $- 9 π$ but isn’t positive. Repeat the step.

$A = - 3 π$

Add $2 π$ to $- 3 π$ .

$A = - 3 π + 2 π$

The resulting angle of $- π$ is coterminal with $- 9 π$ but isn’t positive. Repeat the step.

$A = - π$

Add $2 π$ to $- π$ .

$A = - π + 2 π$

The resulting angle of $π$ is positive and coterminal with $- 9 π$ .

$A = π$

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

$- \cos (0)$

The exact value of $\cos (0)$ is $1$ .

$- 1 \cdot 1$

Multiply $- 1$ by $1$ .

$- 1$

Find the Exact Value cos(-9pi)

Download our
App from the store

Create a High Performed UI/UX Design from a Silicon Valley.

Download our App from the store

Create a High Performed UI/UX Design from a Silicon Valley.

Download our
App from the store