Calculus Examples

$4 \cos (- \frac{π}{4})$

Step 1

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

$4 \cos (\frac{7 π}{4})$

Step 2

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

$4 \cos (\frac{π}{4})$

Step 3

The exact value of $\cos (\frac{π}{4})$ is $\frac{\sqrt{2}}{2}$ .

$4 \frac{\sqrt{2}}{2}$

Step 4

Cancel the common factor of $2$ .

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Step 4.1

Factor $2$ out of $4$ .

$2 (2) \frac{\sqrt{2}}{2}$

Step 4.2

Cancel the common factor.

$2 \cdot 2 \frac{\sqrt{2}}{2}$

Step 4.3

Rewrite the expression.

$2 \sqrt{2}$

Step 5

The result can be shown in multiple forms.

Exact Form:

$2 \sqrt{2}$

Decimal Form:

$2.82842712 \dots$