To find the coordinate of the vertex, set the inside of the absolute value equal to . In this case, .

Solve the equation to find the coordinate for the absolute value vertex.

Take the inverse cosine of both sides of the equation to extract from inside the cosine.

The exact value of is .

The cosine function is positive in the first and fourth quadrants. To find the second solution, subtract the reference angle from to find the solution in the fourth quadrant.

Simplify .

To write as a fraction with a common denominator, multiply by .

Combine fractions.

Combine and .

Combine the numerators over the common denominator.

Simplify the numerator.

Multiply by .

Subtract from .

Find the period of .

The period of the function can be calculated using .

Replace with in the formula for period.

The absolute value is the distance between a number and zero. The distance between and is .

Divide by .

The period of the function is so values will repeat every radians in both directions.

, for any integer

Consolidate the answers.

, for any integer

, for any integer

Replace the variable with in the expression.

The absolute value vertex is .

The domain of the expression is all real numbers except where the expression is undefined. In this case, there is no real number that makes the expression undefined.

Interval Notation:

Set-Builder Notation:

The absolute value can be graphed using the points around the vertex

Graph f(x)=|cos(x)|