Algebra Examples

\cos (x)

$\cos (x)$ ,

x = 7 π

$x = 7 π$

Step 1

Replace the variable

x

$x$ with

7 π

$7 π$ in the expression.

\cos (7 π)

$\cos (7 π)$

Step 2

Subtract full rotations of

2 π

$2 π$ until the angle is greater than or equal to

0

$0$ and less than

2 π

$2 π$ .

\cos (π)

$\cos (π)$

Step 3

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)

$- \cos (0)$

Step 4

The exact value of

\cos (0)

$\cos (0)$ is

1

$1$ .

- 1 \cdot 1

$- 1 \cdot 1$

Step 5

Multiply

- 1

$- 1$ by

1

$1$ .

- 1

$- 1$

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