Trigonometry Examples

$f (x) = \tan (2 x + \frac{π}{6}) - 9$

Step 1

Find the asymptotes.

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Step 1.1

For any $y = \tan (x)$ , vertical asymptotes occur at $x = \frac{π}{2} + n π$ , where $n$ is an integer. Use the basic period for $y = \tan (x)$ , $(- \frac{π}{2}, \frac{π}{2})$ , to find the vertical asymptotes for $y = \tan (2 x + \frac{π}{6}) - 9$ . Set the inside of the tangent function, $b x + c$ , for $y = a \tan (b x + c) + d$ equal to $- \frac{π}{2}$ to find where the vertical asymptote occurs for $y = \tan (2 x + \frac{π}{6}) - 9$ .

$2 x + \frac{π}{6} = - \frac{π}{2}$

Step 1.2

Solve for $x$ .

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Step 1.2.1

Move all terms not containing $x$ to the right side of the equation.

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Step 1.2.1.1

Subtract $\frac{π}{6}$ from both sides of the equation.

$2 x = - \frac{π}{2} - \frac{π}{6}$

Step 1.2.1.2

To write $- \frac{π}{2}$ as a fraction with a common denominator, multiply by $\frac{3}{3}$ .

$2 x = - \frac{π}{2} \cdot \frac{3}{3} - \frac{π}{6}$

Step 1.2.1.3

Write each expression with a common denominator of $6$ , by multiplying each by an appropriate factor of $1$ .

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Step 1.2.1.3.1

Multiply $\frac{π}{2}$ by $\frac{3}{3}$ .

$2 x = - \frac{π \cdot 3}{2 \cdot 3} - \frac{π}{6}$

Step 1.2.1.3.2

Multiply $2$ by $3$ .

$2 x = - \frac{π \cdot 3}{6} - \frac{π}{6}$

Step 1.2.1.4

Combine the numerators over the common denominator.

$2 x = \frac{- π \cdot 3 - π}{6}$

Step 1.2.1.5

Simplify the numerator.

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Step 1.2.1.5.1

Multiply $3$ by $- 1$ .

$2 x = \frac{- 3 π - π}{6}$

Step 1.2.1.5.2

Subtract $π$ from $- 3 π$ .

$2 x = \frac{- 4 π}{6}$

Step 1.2.1.6

Cancel the common factor of $- 4$ and $6$ .

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Step 1.2.1.6.1

Factor $2$ out of $- 4 π$ .

$2 x = \frac{2 (- 2 π)}{6}$

Step 1.2.1.6.2

Cancel the common factors.

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Step 1.2.1.6.2.1

Factor $2$ out of $6$ .

$2 x = \frac{2 (- 2 π)}{2 (3)}$

Step 1.2.1.6.2.2

Cancel the common factor.

$2 x = \frac{2 (- 2 π)}{2 \cdot 3}$

Step 1.2.1.6.2.3

Rewrite the expression.

$2 x = \frac{- 2 π}{3}$

Step 1.2.1.7

Move the negative in front of the fraction.

$2 x = - \frac{2 π}{3}$

Step 1.2.2

Divide each term in $2 x = - \frac{2 π}{3}$ by $2$ and simplify.

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Step 1.2.2.1

Divide each term in $2 x = - \frac{2 π}{3}$ by $2$ .

$\frac{2 x}{2} = \frac{- \frac{2 π}{3}}{2}$

Step 1.2.2.2

Simplify the left side.

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Step 1.2.2.2.1

Cancel the common factor of $2$ .

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Step 1.2.2.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{- \frac{2 π}{3}}{2}$

Step 1.2.2.2.1.2

Divide $x$ by $1$ .

$x = \frac{- \frac{2 π}{3}}{2}$

Step 1.2.2.3

Simplify the right side.

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Step 1.2.2.3.1

Multiply the numerator by the reciprocal of the denominator.

$x = - \frac{2 π}{3} \cdot \frac{1}{2}$

Step 1.2.2.3.2

Cancel the common factor of $2$ .

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Step 1.2.2.3.2.1

Move the leading negative in $- \frac{2 π}{3}$ into the numerator.

$x = \frac{- 2 π}{3} \cdot \frac{1}{2}$

Step 1.2.2.3.2.2

Factor $2$ out of $- 2 π$ .

$x = \frac{2 (- π)}{3} \cdot \frac{1}{2}$

Step 1.2.2.3.2.3

Cancel the common factor.

$x = \frac{2 (- π)}{3} \cdot \frac{1}{2}$

Step 1.2.2.3.2.4

Rewrite the expression.

$x = \frac{- π}{3}$

Step 1.2.2.3.3

Move the negative in front of the fraction.

$x = - \frac{π}{3}$

Step 1.3

Set the inside of the tangent function $2 x + \frac{π}{6}$ equal to $\frac{π}{2}$ .

$2 x + \frac{π}{6} = \frac{π}{2}$

Step 1.4

Solve for $x$ .

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Step 1.4.1

Move all terms not containing $x$ to the right side of the equation.

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Step 1.4.1.1

Subtract $\frac{π}{6}$ from both sides of the equation.

$2 x = \frac{π}{2} - \frac{π}{6}$

Step 1.4.1.2

To write $\frac{π}{2}$ as a fraction with a common denominator, multiply by $\frac{3}{3}$ .

$2 x = \frac{π}{2} \cdot \frac{3}{3} - \frac{π}{6}$

Step 1.4.1.3

Write each expression with a common denominator of $6$ , by multiplying each by an appropriate factor of $1$ .

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Step 1.4.1.3.1

Multiply $\frac{π}{2}$ by $\frac{3}{3}$ .

$2 x = \frac{π \cdot 3}{2 \cdot 3} - \frac{π}{6}$

Step 1.4.1.3.2

Multiply $2$ by $3$ .

$2 x = \frac{π \cdot 3}{6} - \frac{π}{6}$

Step 1.4.1.4

Combine the numerators over the common denominator.

$2 x = \frac{π \cdot 3 - π}{6}$

Step 1.4.1.5

Simplify the numerator.

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Step 1.4.1.5.1

Move $3$ to the left of $π$ .

$2 x = \frac{3 \cdot π - π}{6}$

Step 1.4.1.5.2

Subtract $π$ from $3 π$ .

$2 x = \frac{2 π}{6}$

Step 1.4.1.6

Cancel the common factor of $2$ and $6$ .

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Step 1.4.1.6.1

Factor $2$ out of $2 π$ .

$2 x = \frac{2 (π)}{6}$

Step 1.4.1.6.2

Cancel the common factors.

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Step 1.4.1.6.2.1

Factor $2$ out of $6$ .

$2 x = \frac{2 π}{2 \cdot 3}$

Step 1.4.1.6.2.2

Cancel the common factor.

$2 x = \frac{2 π}{2 \cdot 3}$

Step 1.4.1.6.2.3

Rewrite the expression.

$2 x = \frac{π}{3}$

Step 1.4.2

Divide each term in $2 x = \frac{π}{3}$ by $2$ and simplify.

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Step 1.4.2.1

Divide each term in $2 x = \frac{π}{3}$ by $2$ .

$\frac{2 x}{2} = \frac{\frac{π}{3}}{2}$

Step 1.4.2.2

Simplify the left side.

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Step 1.4.2.2.1

Cancel the common factor of $2$ .

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Step 1.4.2.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{\frac{π}{3}}{2}$

Step 1.4.2.2.1.2

Divide $x$ by $1$ .

$x = \frac{\frac{π}{3}}{2}$

Step 1.4.2.3

Simplify the right side.

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Step 1.4.2.3.1

Multiply the numerator by the reciprocal of the denominator.

$x = \frac{π}{3} \cdot \frac{1}{2}$

Step 1.4.2.3.2

Multiply $\frac{π}{3} \cdot \frac{1}{2}$ .

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Step 1.4.2.3.2.1

Multiply $\frac{π}{3}$ by $\frac{1}{2}$ .

$x = \frac{π}{3 \cdot 2}$

Step 1.4.2.3.2.2

Multiply $3$ by $2$ .

$x = \frac{π}{6}$

Step 1.5

The basic period for $y = \tan (2 x + \frac{π}{6}) - 9$ will occur at $(- \frac{π}{3}, \frac{π}{6})$ , where $- \frac{π}{3}$ and $\frac{π}{6}$ are vertical asymptotes.

$(- \frac{π}{3}, \frac{π}{6})$

Step 1.6

The absolute value is the distance between a number and zero. The distance between $0$ and $2$ is $2$ .

$\frac{π}{2}$

Step 1.7

The vertical asymptotes for $y = \tan (2 x + \frac{π}{6}) - 9$ occur at $- \frac{π}{3}$ , $\frac{π}{6}$ , and every $x = - \frac{π}{3} + \frac{π n}{2}$ , where $n$ is an integer.

$x = - \frac{π}{3} + \frac{π n}{2}$

Step 1.8

Tangent only has vertical asymptotes.

No Horizontal Asymptotes

No Oblique Asymptotes

Vertical Asymptotes: $x = - \frac{π}{3} + \frac{π n}{2}$ where $n$ is an integer

No Horizontal Asymptotes

No Oblique Asymptotes

Vertical Asymptotes: $x = - \frac{π}{3} + \frac{π n}{2}$ where $n$ is an integer

Step 2

Use the form $a \tan (b x - c) + d$ to find the variables used to find the amplitude, period, phase shift, and vertical shift.

$a = 1$

$b = 2$

$c = - \frac{π}{6}$

$d = - 9$

Step 3

Since the graph of the function $t a n$ does not have a maximum or minimum value, there can be no value for the amplitude.

Amplitude: None

Step 4

Find the period using the formula $\frac{π}{| b |}$ .

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Step 4.1

Find the period of $\tan (2 x + \frac{π}{6})$ .

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Step 4.1.1

The period of the function can be calculated using $\frac{π}{| b |}$ .

$\frac{π}{| b |}$

Step 4.1.2

Replace $b$ with $2$ in the formula for period.

$\frac{π}{| 2 |}$

Step 4.1.3

The absolute value is the distance between a number and zero. The distance between $0$ and $2$ is $2$ .

$\frac{π}{2}$

Step 4.2

Find the period of $- 9$ .

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Step 4.2.1

The period of the function can be calculated using $\frac{π}{| b |}$ .

$\frac{π}{| b |}$

Step 4.2.2

Replace $b$ with $2$ in the formula for period.

$\frac{π}{| 2 |}$

Step 4.2.3

The absolute value is the distance between a number and zero. The distance between $0$ and $2$ is $2$ .

$\frac{π}{2}$

Step 4.3

The period of addition/subtraction of trig functions is the maximum of the individual periods.

$\frac{π}{2}$

Step 5

Find the phase shift using the formula $\frac{c}{b}$ .

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Step 5.1

The phase shift of the function can be calculated from $\frac{c}{b}$ .

Phase Shift: $\frac{c}{b}$

Step 5.2

Replace the values of $c$ and $b$ in the equation for phase shift.

Phase Shift: $\frac{- \frac{π}{6}}{2}$

Step 5.3

Multiply the numerator by the reciprocal of the denominator.

Phase Shift: $- \frac{π}{6} \cdot \frac{1}{2}$

Step 5.4

Multiply $- \frac{π}{6} \cdot \frac{1}{2}$ .

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Step 5.4.1

Multiply $\frac{1}{2}$ by $\frac{π}{6}$ .

Phase Shift: $- \frac{π}{2 \cdot 6}$

Step 5.4.2

Multiply $2$ by $6$ .

Phase Shift: $- \frac{π}{12}$

Step 6

List the properties of the trigonometric function.

Amplitude: None

Period: $\frac{π}{2}$

Phase Shift: $- \frac{π}{12}$ ( $\frac{π}{12}$ to the left)

Vertical Shift: $- 9$

Step 7

The trig function can be graphed using the amplitude, period, phase shift, vertical shift, and the points.

Vertical Asymptotes: $x = - \frac{π}{3} + \frac{π n}{2}$ where $n$ is an integer

Amplitude: None

Period: $\frac{π}{2}$

Phase Shift: $- \frac{π}{12}$ ( $\frac{π}{12}$ to the left)

Vertical Shift: $- 9$

Step 8