Trigonometry Examples

$4 \sin^{2} (2 x) = 1$

Step 1

Divide each term in $4 \sin^{2} (2 x) = 1$ by $4$ and simplify.

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Step 1.1

Divide each term in $4 \sin^{2} (2 x) = 1$ by $4$ .

$\frac{4 \sin^{2} (2 x)}{4} = \frac{1}{4}$

Step 1.2

Simplify the left side.

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Step 1.2.1

Cancel the common factor of $4$ .

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Step 1.2.1.1

Cancel the common factor.

$\frac{4 \sin^{2} (2 x)}{4} = \frac{1}{4}$

Step 1.2.1.2

Divide $\sin^{2} (2 x)$ by $1$ .

$\sin^{2} (2 x) = \frac{1}{4}$

Step 2

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$\sin (2 x) = \pm \sqrt{\frac{1}{4}}$

Step 3

Simplify $\pm \sqrt{\frac{1}{4}}$ .

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Step 3.1

Rewrite $\sqrt{\frac{1}{4}}$ as $\frac{\sqrt{1}}{\sqrt{4}}$ .

$\sin (2 x) = \pm \frac{\sqrt{1}}{\sqrt{4}}$

Step 3.2

Any root of $1$ is $1$ .

$\sin (2 x) = \pm \frac{1}{\sqrt{4}}$

Step 3.3

Simplify the denominator.

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Step 3.3.1

Rewrite $4$ as $2^{2}$ .

$\sin (2 x) = \pm \frac{1}{\sqrt{2^{2}}}$

Step 3.3.2

Pull terms out from under the radical, assuming positive real numbers.

$\sin (2 x) = \pm \frac{1}{2}$

Step 4

The complete solution is the result of both the positive and negative portions of the solution.

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Step 4.1

First, use the positive value of the $\pm$ to find the first solution.

$\sin (2 x) = \frac{1}{2}$

Step 4.2

Next, use the negative value of the $\pm$ to find the second solution.

$\sin (2 x) = - \frac{1}{2}$

Step 4.3

The complete solution is the result of both the positive and negative portions of the solution.

$\sin (2 x) = \frac{1}{2}, - \frac{1}{2}$

Step 5

Set up each of the solutions to solve for $x$ .

$\sin (2 x) = \frac{1}{2}$

$\sin (2 x) = - \frac{1}{2}$

Step 6

Solve for $x$ in $\sin (2 x) = \frac{1}{2}$ .

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Step 6.1

Take the inverse sine of both sides of the equation to extract $x$ from inside the sine.

$2 x = \arcsin (\frac{1}{2})$

Step 6.2

Simplify the right side.

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Step 6.2.1

The exact value of $\arcsin (\frac{1}{2})$ is $\frac{π}{6}$ .

$2 x = \frac{π}{6}$

Step 6.3

Divide each term in $2 x = \frac{π}{6}$ by $2$ and simplify.

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Step 6.3.1

Divide each term in $2 x = \frac{π}{6}$ by $2$ .

$\frac{2 x}{2} = \frac{\frac{π}{6}}{2}$

Step 6.3.2

Simplify the left side.

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Step 6.3.2.1

Cancel the common factor of $2$ .

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Step 6.3.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{\frac{π}{6}}{2}$

Step 6.3.2.1.2

Divide $x$ by $1$ .

$x = \frac{\frac{π}{6}}{2}$

Step 6.3.3

Simplify the right side.

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Step 6.3.3.1

Multiply the numerator by the reciprocal of the denominator.

$x = \frac{π}{6} \cdot \frac{1}{2}$

Step 6.3.3.2

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

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Step 6.3.3.2.1

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

$x = \frac{π}{6 \cdot 2}$

Step 6.3.3.2.2

Multiply $6$ by $2$ .

$x = \frac{π}{12}$

Step 6.4

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

$2 x = π - \frac{π}{6}$

Step 6.5

Solve for $x$ .

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Step 6.5.1

Simplify.

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Step 6.5.1.1

To write $π$ as a fraction with a common denominator, multiply by $\frac{6}{6}$ .

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

Step 6.5.1.2

Combine $π$ and $\frac{6}{6}$ .

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

Step 6.5.1.3

Combine the numerators over the common denominator.

$2 x = \frac{π \cdot 6 - π}{6}$

Step 6.5.1.4

Subtract $π$ from $π \cdot 6$ .

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Step 6.5.1.4.1

Reorder $π$ and $6$ .

$2 x = \frac{6 \cdot π - π}{6}$

Step 6.5.1.4.2

Subtract $π$ from $6 \cdot π$ .

$2 x = \frac{5 \cdot π}{6}$

Step 6.5.2

Divide each term in $2 x = \frac{5 \cdot π}{6}$ by $2$ and simplify.

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Step 6.5.2.1

Divide each term in $2 x = \frac{5 \cdot π}{6}$ by $2$ .

$\frac{2 x}{2} = \frac{\frac{5 \cdot π}{6}}{2}$

Step 6.5.2.2

Simplify the left side.

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Step 6.5.2.2.1

Cancel the common factor of $2$ .

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Step 6.5.2.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{\frac{5 \cdot π}{6}}{2}$

Step 6.5.2.2.1.2

Divide $x$ by $1$ .

$x = \frac{\frac{5 \cdot π}{6}}{2}$

Step 6.5.2.3

Simplify the right side.

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Step 6.5.2.3.1

Multiply the numerator by the reciprocal of the denominator.

$x = \frac{5 \cdot π}{6} \cdot \frac{1}{2}$

Step 6.5.2.3.2

Multiply $\frac{5 π}{6} \cdot \frac{1}{2}$ .

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Step 6.5.2.3.2.1

Multiply $\frac{5 π}{6}$ by $\frac{1}{2}$ .

$x = \frac{5 π}{6 \cdot 2}$

Step 6.5.2.3.2.2

Multiply $6$ by $2$ .

$x = \frac{5 π}{12}$

Step 6.6

Find the period of $\sin (2 x)$ .

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Step 6.6.1

The period of the function can be calculated using $\frac{2 π}{| b |}$ .

$\frac{2 π}{| b |}$

Step 6.6.2

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

$\frac{2 π}{| 2 |}$

Step 6.6.3

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

$\frac{2 π}{2}$

Step 6.6.4

Cancel the common factor of $2$ .

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Step 6.6.4.1

Cancel the common factor.

$\frac{2 π}{2}$

Step 6.6.4.2

Divide $π$ by $1$ .

$π$

Step 6.7

The period of the $\sin (2 x)$ function is $π$ so values will repeat every $π$ radians in both directions.

$x = \frac{π}{12} + π n, \frac{5 π}{12} + π n$ , for any integer $n$

Step 7

Solve for $x$ in $\sin (2 x) = - \frac{1}{2}$ .

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Step 7.1

Take the inverse sine of both sides of the equation to extract $x$ from inside the sine.

$2 x = \arcsin (- \frac{1}{2})$

Step 7.2

Simplify the right side.

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Step 7.2.1

The exact value of $\arcsin (- \frac{1}{2})$ is $- \frac{π}{6}$ .

$2 x = - \frac{π}{6}$

Step 7.3

Divide each term in $2 x = - \frac{π}{6}$ by $2$ and simplify.

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Step 7.3.1

Divide each term in $2 x = - \frac{π}{6}$ by $2$ .

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

Step 7.3.2

Simplify the left side.

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Step 7.3.2.1

Cancel the common factor of $2$ .

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Step 7.3.2.1.1

Cancel the common factor.

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

Step 7.3.2.1.2

Divide $x$ by $1$ .

$x = \frac{- \frac{π}{6}}{2}$

Step 7.3.3

Simplify the right side.

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Step 7.3.3.1

Multiply the numerator by the reciprocal of the denominator.

$x = - \frac{π}{6} \cdot \frac{1}{2}$

Step 7.3.3.2

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

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Step 7.3.3.2.1

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

$x = - \frac{π}{2 \cdot 6}$

Step 7.3.3.2.2

Multiply $2$ by $6$ .

$x = - \frac{π}{12}$

Step 7.4

The sine function is negative in the third and fourth quadrants. To find the second solution, subtract the solution from $2 π$ , to find a reference angle. Next, add this reference angle to $π$ to find the solution in the third quadrant.

$2 x = 2 π + \frac{π}{6} + π$

Step 7.5

Simplify the expression to find the second solution.

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Step 7.5.1

Subtract $2 π$ from $2 π + \frac{π}{6} + π$ .

$2 x = 2 π + \frac{π}{6} + π - 2 π$

Step 7.5.2

The resulting angle of $\frac{7 π}{6}$ is positive, less than $2 π$ , and coterminal with $2 π + \frac{π}{6} + π$ .

$2 x = \frac{7 π}{6}$

Step 7.5.3

Divide each term in $2 x = \frac{7 π}{6}$ by $2$ and simplify.

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Step 7.5.3.1

Divide each term in $2 x = \frac{7 π}{6}$ by $2$ .

$\frac{2 x}{2} = \frac{\frac{7 π}{6}}{2}$

Step 7.5.3.2

Simplify the left side.

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Step 7.5.3.2.1

Cancel the common factor of $2$ .

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Step 7.5.3.2.1.1

Cancel the common factor.

$\frac{2 x}{2} = \frac{\frac{7 π}{6}}{2}$

Step 7.5.3.2.1.2

Divide $x$ by $1$ .

$x = \frac{\frac{7 π}{6}}{2}$

Step 7.5.3.3

Simplify the right side.

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Step 7.5.3.3.1

Multiply the numerator by the reciprocal of the denominator.

$x = \frac{7 π}{6} \cdot \frac{1}{2}$

Step 7.5.3.3.2

Multiply $\frac{7 π}{6} \cdot \frac{1}{2}$ .

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Step 7.5.3.3.2.1

Multiply $\frac{7 π}{6}$ by $\frac{1}{2}$ .

$x = \frac{7 π}{6 \cdot 2}$

Step 7.5.3.3.2.2

Multiply $6$ by $2$ .

$x = \frac{7 π}{12}$

Step 7.6

Find the period of $\sin (2 x)$ .

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Step 7.6.1

The period of the function can be calculated using $\frac{2 π}{| b |}$ .

$\frac{2 π}{| b |}$

Step 7.6.2

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

$\frac{2 π}{| 2 |}$

Step 7.6.3

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

$\frac{2 π}{2}$

Step 7.6.4

Cancel the common factor of $2$ .

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Step 7.6.4.1

Cancel the common factor.

$\frac{2 π}{2}$

Step 7.6.4.2

Divide $π$ by $1$ .

$π$

Step 7.7

Add $π$ to every negative angle to get positive angles.

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Step 7.7.1

Add $π$ to $- \frac{π}{12}$ to find the positive angle.

$- \frac{π}{12} + π$

Step 7.7.2

To write $π$ as a fraction with a common denominator, multiply by $\frac{12}{12}$ .

$π \cdot \frac{12}{12} - \frac{π}{12}$

Step 7.7.3

Combine fractions.

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Step 7.7.3.1

Combine $π$ and $\frac{12}{12}$ .

$\frac{π \cdot 12}{12} - \frac{π}{12}$

Step 7.7.3.2

Combine the numerators over the common denominator.

$\frac{π \cdot 12 - π}{12}$

Step 7.7.4

Simplify the numerator.

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Step 7.7.4.1

Move $12$ to the left of $π$ .

$\frac{12 \cdot π - π}{12}$

Step 7.7.4.2

Subtract $π$ from $12 π$ .

$\frac{11 π}{12}$

Step 7.7.5

List the new angles.

$x = \frac{11 π}{12}$

Step 7.8

The period of the $\sin (2 x)$ function is $π$ so values will repeat every $π$ radians in both directions.

$x = \frac{7 π}{12} + π n, \frac{11 π}{12} + π n$ , for any integer $n$

Step 8

List all of the solutions.

$x = \frac{π}{12} + π n, \frac{5 π}{12} + π n, \frac{7 π}{12} + π n, \frac{11 π}{12} + π n$ , for any integer $n$

Step 9

Consolidate the solutions.

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Step 9.1

Consolidate $\frac{π}{12} + π n$ and $\frac{7 π}{12} + π n$ to $\frac{π}{12} + \frac{π n}{2}$ .

$x = \frac{π}{12} + \frac{π n}{2}, \frac{5 π}{12} + π n, \frac{11 π}{12} + π n$ , for any integer $n$

Step 9.2

Consolidate $\frac{5 π}{12} + π n$ and $\frac{11 π}{12} + π n$ to $\frac{5 π}{12} + \frac{π n}{2}$ .

$x = \frac{π}{12} + \frac{π n}{2}, \frac{5 π}{12} + \frac{π n}{2}$ , for any integer $n$