Calculus Examples

Find the Critical Points 36x-9tan(x)
Step 1
Find the first derivative.
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Step 1.1
Find the first derivative.
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Step 1.1.1
By the Sum Rule, the derivative of with respect to is .
Step 1.1.2
Evaluate .
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Step 1.1.2.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.2.2
Differentiate using the Power Rule which states that is where .
Step 1.1.2.3
Multiply by .
Step 1.1.3
Evaluate .
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Step 1.1.3.1
Since is constant with respect to , the derivative of with respect to is .
Step 1.1.3.2
The derivative of with respect to is .
Step 1.2
The first derivative of with respect to is .
Step 2
Set the first derivative equal to then solve the equation .
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Step 2.1
Set the first derivative equal to .
Step 2.2
Subtract from both sides of the equation.
Step 2.3
Divide each term in by and simplify.
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Step 2.3.1
Divide each term in by .
Step 2.3.2
Simplify the left side.
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Step 2.3.2.1
Cancel the common factor of .
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Step 2.3.2.1.1
Cancel the common factor.
Step 2.3.2.1.2
Divide by .
Step 2.3.3
Simplify the right side.
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Step 2.3.3.1
Divide by .
Step 2.4
Take the specified root of both sides of the equation to eliminate the exponent on the left side.
Step 2.5
Simplify .
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Step 2.5.1
Rewrite as .
Step 2.5.2
Pull terms out from under the radical, assuming positive real numbers.
Step 2.6
The complete solution is the result of both the positive and negative portions of the solution.
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Step 2.6.1
First, use the positive value of the to find the first solution.
Step 2.6.2
Next, use the negative value of the to find the second solution.
Step 2.6.3
The complete solution is the result of both the positive and negative portions of the solution.
Step 2.7
Set up each of the solutions to solve for .
Step 2.8
Solve for in .
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Step 2.8.1
Take the inverse secant of both sides of the equation to extract from inside the secant.
Step 2.8.2
Simplify the right side.
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Step 2.8.2.1
The exact value of is .
Step 2.8.3
The secant 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.
Step 2.8.4
Simplify .
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Step 2.8.4.1
To write as a fraction with a common denominator, multiply by .
Step 2.8.4.2
Combine fractions.
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Step 2.8.4.2.1
Combine and .
Step 2.8.4.2.2
Combine the numerators over the common denominator.
Step 2.8.4.3
Simplify the numerator.
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Step 2.8.4.3.1
Multiply by .
Step 2.8.4.3.2
Subtract from .
Step 2.8.5
Find the period of .
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Step 2.8.5.1
The period of the function can be calculated using .
Step 2.8.5.2
Replace with in the formula for period.
Step 2.8.5.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 2.8.5.4
Divide by .
Step 2.8.6
The period of the function is so values will repeat every radians in both directions.
, for any integer
, for any integer
Step 2.9
Solve for in .
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Step 2.9.1
Take the inverse secant of both sides of the equation to extract from inside the secant.
Step 2.9.2
Simplify the right side.
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Step 2.9.2.1
The exact value of is .
Step 2.9.3
The secant function is negative in the second and third quadrants. To find the second solution, subtract the reference angle from to find the solution in the third quadrant.
Step 2.9.4
Simplify .
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Step 2.9.4.1
To write as a fraction with a common denominator, multiply by .
Step 2.9.4.2
Combine fractions.
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Step 2.9.4.2.1
Combine and .
Step 2.9.4.2.2
Combine the numerators over the common denominator.
Step 2.9.4.3
Simplify the numerator.
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Step 2.9.4.3.1
Multiply by .
Step 2.9.4.3.2
Subtract from .
Step 2.9.5
Find the period of .
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Step 2.9.5.1
The period of the function can be calculated using .
Step 2.9.5.2
Replace with in the formula for period.
Step 2.9.5.3
The absolute value is the distance between a number and zero. The distance between and is .
Step 2.9.5.4
Divide by .
Step 2.9.6
The period of the function is so values will repeat every radians in both directions.
, for any integer
, for any integer
Step 2.10
List all of the solutions.
, for any integer
, for any integer
Step 3
Find the values where the derivative is undefined.
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Step 3.1
Set the argument in equal to to find where the expression is undefined.
, for any integer
Step 3.2
The equation is undefined where the denominator equals , the argument of a square root is less than , or the argument of a logarithm is less than or equal to .
, for any integer
, for any integer
Step 4
Evaluate at each value where the derivative is or undefined.
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Step 4.1
Evaluate at .
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Step 4.1.1
Substitute for .
Step 4.1.2
Simplify each term.
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Step 4.1.2.1
Cancel the common factor of .
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Step 4.1.2.1.1
Factor out of .
Step 4.1.2.1.2
Cancel the common factor.
Step 4.1.2.1.3
Rewrite the expression.
Step 4.1.2.2
The exact value of is .
Step 4.2
Evaluate at .
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Step 4.2.1
Substitute for .
Step 4.2.2
Simplify each term.
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Step 4.2.2.1
Cancel the common factor of .
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Step 4.2.2.1.1
Factor out of .
Step 4.2.2.1.2
Cancel the common factor.
Step 4.2.2.1.3
Rewrite the expression.
Step 4.2.2.2
Multiply by .
Step 4.2.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.2.2.4
The exact value of is .
Step 4.3
Evaluate at .
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Step 4.3.1
Substitute for .
Step 4.3.2
Simplify each term.
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Step 4.3.2.1
Cancel the common factor of .
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Step 4.3.2.1.1
Factor out of .
Step 4.3.2.1.2
Cancel the common factor.
Step 4.3.2.1.3
Rewrite the expression.
Step 4.3.2.2
Multiply by .
Step 4.3.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.3.2.4
The exact value of is .
Step 4.4
Evaluate at .
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Step 4.4.1
Substitute for .
Step 4.4.2
Simplify each term.
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Step 4.4.2.1
Cancel the common factor of .
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Step 4.4.2.1.1
Factor out of .
Step 4.4.2.1.2
Cancel the common factor.
Step 4.4.2.1.3
Rewrite the expression.
Step 4.4.2.2
Multiply by .
Step 4.4.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.4.2.4
The exact value of is .
Step 4.5
Evaluate at .
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Step 4.5.1
Substitute for .
Step 4.5.2
Simplify each term.
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Step 4.5.2.1
Cancel the common factor of .
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Step 4.5.2.1.1
Factor out of .
Step 4.5.2.1.2
Cancel the common factor.
Step 4.5.2.1.3
Rewrite the expression.
Step 4.5.2.2
Multiply by .
Step 4.5.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.5.2.4
The exact value of is .
Step 4.6
Evaluate at .
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Step 4.6.1
Substitute for .
Step 4.6.2
Simplify each term.
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Step 4.6.2.1
Cancel the common factor of .
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Step 4.6.2.1.1
Factor out of .
Step 4.6.2.1.2
Cancel the common factor.
Step 4.6.2.1.3
Rewrite the expression.
Step 4.6.2.2
Multiply by .
Step 4.6.2.3
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the fourth quadrant.
Step 4.6.2.4
The exact value of is .
Step 4.6.2.5
Multiply by .
Step 4.7
Evaluate at .
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Step 4.7.1
Substitute for .
Step 4.7.2
Simplify each term.
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Step 4.7.2.1
Cancel the common factor of .
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Step 4.7.2.1.1
Factor out of .
Step 4.7.2.1.2
Cancel the common factor.
Step 4.7.2.1.3
Rewrite the expression.
Step 4.7.2.2
Multiply by .
Step 4.7.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.7.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the fourth quadrant.
Step 4.7.2.5
The exact value of is .
Step 4.7.2.6
Multiply by .
Step 4.8
Evaluate at .
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Step 4.8.1
Substitute for .
Step 4.8.2
Simplify each term.
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Step 4.8.2.1
Cancel the common factor of .
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Step 4.8.2.1.1
Factor out of .
Step 4.8.2.1.2
Cancel the common factor.
Step 4.8.2.1.3
Rewrite the expression.
Step 4.8.2.2
Multiply by .
Step 4.8.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.8.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the fourth quadrant.
Step 4.8.2.5
The exact value of is .
Step 4.8.2.6
Multiply by .
Step 4.9
Evaluate at .
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Step 4.9.1
Substitute for .
Step 4.9.2
Simplify each term.
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Step 4.9.2.1
Cancel the common factor of .
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Step 4.9.2.1.1
Factor out of .
Step 4.9.2.1.2
Cancel the common factor.
Step 4.9.2.1.3
Rewrite the expression.
Step 4.9.2.2
Multiply by .
Step 4.9.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.9.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the fourth quadrant.
Step 4.9.2.5
The exact value of is .
Step 4.9.2.6
Multiply by .
Step 4.10
Evaluate at .
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Step 4.10.1
Substitute for .
Step 4.10.2
Simplify each term.
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Step 4.10.2.1
Cancel the common factor of .
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Step 4.10.2.1.1
Factor out of .
Step 4.10.2.1.2
Cancel the common factor.
Step 4.10.2.1.3
Rewrite the expression.
Step 4.10.2.2
Multiply by .
Step 4.10.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.10.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the fourth quadrant.
Step 4.10.2.5
The exact value of is .
Step 4.10.2.6
Multiply by .
Step 4.11
Evaluate at .
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Step 4.11.1
Substitute for .
Step 4.11.2
Simplify each term.
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Step 4.11.2.1
Cancel the common factor of .
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Step 4.11.2.1.1
Factor out of .
Step 4.11.2.1.2
Cancel the common factor.
Step 4.11.2.1.3
Rewrite the expression.
Step 4.11.2.2
Multiply by .
Step 4.11.2.3
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the second quadrant.
Step 4.11.2.4
The exact value of is .
Step 4.11.2.5
Multiply by .
Step 4.12
Evaluate at .
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Step 4.12.1
Substitute for .
Step 4.12.2
Simplify each term.
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Step 4.12.2.1
Cancel the common factor of .
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Step 4.12.2.1.1
Factor out of .
Step 4.12.2.1.2
Cancel the common factor.
Step 4.12.2.1.3
Rewrite the expression.
Step 4.12.2.2
Multiply by .
Step 4.12.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.12.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the second quadrant.
Step 4.12.2.5
The exact value of is .
Step 4.12.2.6
Multiply by .
Step 4.13
Evaluate at .
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Step 4.13.1
Substitute for .
Step 4.13.2
Simplify each term.
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Step 4.13.2.1
Cancel the common factor of .
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Step 4.13.2.1.1
Factor out of .
Step 4.13.2.1.2
Cancel the common factor.
Step 4.13.2.1.3
Rewrite the expression.
Step 4.13.2.2
Multiply by .
Step 4.13.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.13.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the second quadrant.
Step 4.13.2.5
The exact value of is .
Step 4.13.2.6
Multiply by .
Step 4.14
Evaluate at .
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Step 4.14.1
Substitute for .
Step 4.14.2
Simplify each term.
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Step 4.14.2.1
Cancel the common factor of .
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Step 4.14.2.1.1
Factor out of .
Step 4.14.2.1.2
Cancel the common factor.
Step 4.14.2.1.3
Rewrite the expression.
Step 4.14.2.2
Multiply by .
Step 4.14.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.14.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the second quadrant.
Step 4.14.2.5
The exact value of is .
Step 4.14.2.6
Multiply by .
Step 4.15
Evaluate at .
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Step 4.15.1
Substitute for .
Step 4.15.2
Simplify each term.
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Step 4.15.2.1
Cancel the common factor of .
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Step 4.15.2.1.1
Factor out of .
Step 4.15.2.1.2
Cancel the common factor.
Step 4.15.2.1.3
Rewrite the expression.
Step 4.15.2.2
Multiply by .
Step 4.15.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.15.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because tangent is negative in the second quadrant.
Step 4.15.2.5
The exact value of is .
Step 4.15.2.6
Multiply by .
Step 4.16
Evaluate at .
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Step 4.16.1
Substitute for .
Step 4.16.2
Simplify each term.
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Step 4.16.2.1
Cancel the common factor of .
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Step 4.16.2.1.1
Factor out of .
Step 4.16.2.1.2
Cancel the common factor.
Step 4.16.2.1.3
Rewrite the expression.
Step 4.16.2.2
Multiply by .
Step 4.16.2.3
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 4.16.2.4
The exact value of is .
Step 4.17
Evaluate at .
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Step 4.17.1
Substitute for .
Step 4.17.2
Simplify each term.
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Step 4.17.2.1
Cancel the common factor of .
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Step 4.17.2.1.1
Factor out of .
Step 4.17.2.1.2
Cancel the common factor.
Step 4.17.2.1.3
Rewrite the expression.
Step 4.17.2.2
Multiply by .
Step 4.17.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.17.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 4.17.2.5
The exact value of is .
Step 4.18
Evaluate at .
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Step 4.18.1
Substitute for .
Step 4.18.2
Simplify each term.
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Step 4.18.2.1
Cancel the common factor of .
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Step 4.18.2.1.1
Factor out of .
Step 4.18.2.1.2
Cancel the common factor.
Step 4.18.2.1.3
Rewrite the expression.
Step 4.18.2.2
Multiply by .
Step 4.18.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.18.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 4.18.2.5
The exact value of is .
Step 4.19
Evaluate at .
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Step 4.19.1
Substitute for .
Step 4.19.2
Simplify each term.
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Step 4.19.2.1
Cancel the common factor of .
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Step 4.19.2.1.1
Factor out of .
Step 4.19.2.1.2
Cancel the common factor.
Step 4.19.2.1.3
Rewrite the expression.
Step 4.19.2.2
Multiply by .
Step 4.19.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.19.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 4.19.2.5
The exact value of is .
Step 4.20
Evaluate at .
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Step 4.20.1
Substitute for .
Step 4.20.2
Simplify each term.
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Step 4.20.2.1
Cancel the common factor of .
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Step 4.20.2.1.1
Factor out of .
Step 4.20.2.1.2
Cancel the common factor.
Step 4.20.2.1.3
Rewrite the expression.
Step 4.20.2.2
Multiply by .
Step 4.20.2.3
Subtract full rotations of until the angle is greater than or equal to and less than .
Step 4.20.2.4
Apply the reference angle by finding the angle with equivalent trig values in the first quadrant.
Step 4.20.2.5
The exact value of is .
Step 4.21
List all of the points.
Step 5