Trigonometry Examples

$\tan (2 \arccos (x))$

Step 1

Apply the tangent double-angle identity.

$\frac{2 \tan (\arccos (x))}{1 - \tan^{2} (\arccos (x))}$

Step 2

Simplify the numerator.

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Step 2.1

Draw a triangle in the plane with vertices $(x, \sqrt{1^{2} - x^{2}})$ , $(x, 0)$ , and the origin. Then $\arccos (x)$ is the angle between the positive x-axis and the ray beginning at the origin and passing through $(x, \sqrt{1^{2} - x^{2}})$ . Therefore, $\tan (\arccos (x))$ is $\frac{\sqrt{1 - x^{2}}}{x}$ .

$\frac{2 \frac{\sqrt{1 - x^{2}}}{x}}{1 - \tan^{2} (\arccos (x))}$

Step 2.2

Simplify the numerator.

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Step 2.2.1

Rewrite $1$ as $1^{2}$ .

$\frac{2 \frac{\sqrt{1^{2} - x^{2}}}{x}}{1 - \tan^{2} (\arccos (x))}$

Step 2.2.2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 1$ and $b = x$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{1 - \tan^{2} (\arccos (x))}$

Step 3

Simplify the denominator.

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Step 3.1

Rewrite $1$ as $1^{2}$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{1^{2} - \tan^{2} (\arccos (x))}$

Step 3.2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 1$ and $b = \tan (\arccos (x))$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{(1 + \tan (\arccos (x))) (1 - \tan (\arccos (x)))}$

Step 3.3

Simplify.

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Step 3.3.1

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{(1 + \frac{\sqrt{1 - x^{2}}}{x}) (1 - \tan (\arccos (x)))}$

Step 3.3.2

Simplify the numerator.

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Step 3.3.2.1

Rewrite $1$ as $1^{2}$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{(1 + \frac{\sqrt{1^{2} - x^{2}}}{x}) (1 - \tan (\arccos (x)))}$

Step 3.3.2.2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 1$ and $b = x$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{(1 + \frac{\sqrt{(1 + x) (1 - x)}}{x}) (1 - \tan (\arccos (x)))}$

Step 3.3.3

Write $1$ as a fraction with a common denominator.

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{(\frac{x}{x} + \frac{\sqrt{(1 + x) (1 - x)}}{x}) (1 - \tan (\arccos (x)))}$

Step 3.3.4

Combine the numerators over the common denominator.

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} (1 - \tan (\arccos (x)))}$

Step 3.3.5

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} (1 - \frac{\sqrt{1 - x^{2}}}{x})}$

Step 3.3.6

Simplify the numerator.

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Step 3.3.6.1

Rewrite $1$ as $1^{2}$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} (1 - \frac{\sqrt{1^{2} - x^{2}}}{x})}$

Step 3.3.6.2

Since both terms are perfect squares, factor using the difference of squares formula, $a^{2} - b^{2} = (a + b) (a - b)$ where $a = 1$ and $b = x$ .

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} (1 - \frac{\sqrt{(1 + x) (1 - x)}}{x})}$

Step 3.3.7

Write $1$ as a fraction with a common denominator.

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} (\frac{x}{x} - \frac{\sqrt{(1 + x) (1 - x)}}{x})}$

Step 3.3.8

Combine the numerators over the common denominator.

$\frac{2 \frac{\sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} \cdot \frac{x - \sqrt{(1 + x) (1 - x)}}{x}}$

Step 4

Combine fractions.

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Step 4.1

Combine $2$ and $\frac{\sqrt{(1 + x) (1 - x)}}{x}$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x + \sqrt{(1 + x) (1 - x)}}{x} \cdot \frac{x - \sqrt{(1 + x) (1 - x)}}{x}}$

Step 4.2

Multiply $\frac{x + \sqrt{(1 + x) (1 - x)}}{x}$ by $\frac{x - \sqrt{(1 + x) (1 - x)}}{x}$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{(x + \sqrt{(1 + x) (1 - x)}) (x - \sqrt{(1 + x) (1 - x)})}{x \cdot x}}$

Step 5

Simplify the denominator.

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Step 5.1

Raise $x$ to the power of $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{(x + \sqrt{(1 + x) (1 - x)}) (x - \sqrt{(1 + x) (1 - x)})}{x^{1} x}}$

Step 5.2

Raise $x$ to the power of $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{(x + \sqrt{(1 + x) (1 - x)}) (x - \sqrt{(1 + x) (1 - x)})}{x^{1} x^{1}}}$

Step 5.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{(x + \sqrt{(1 + x) (1 - x)}) (x - \sqrt{(1 + x) (1 - x)})}{x^{1 + 1}}}$

Step 5.4

Add $1$ and $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{(x + \sqrt{(1 + x) (1 - x)}) (x - \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6

Simplify the denominator.

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Step 6.1

Expand $(x + \sqrt{(1 + x) (1 - x)}) (x - \sqrt{(1 + x) (1 - x)})$ using the FOIL Method.

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Step 6.1.1

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x (x - \sqrt{(1 + x) (1 - x)}) + \sqrt{(1 + x) (1 - x)} (x - \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.1.2

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x \cdot x + x (- \sqrt{(1 + x) (1 - x)}) + \sqrt{(1 + x) (1 - x)} (x - \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.1.3

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x \cdot x + x (- \sqrt{(1 + x) (1 - x)}) + \sqrt{(1 + x) (1 - x)} x + \sqrt{(1 + x) (1 - x)} (- \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.2

Combine the opposite terms in $x \cdot x + x (- \sqrt{(1 + x) (1 - x)}) + \sqrt{(1 + x) (1 - x)} x + \sqrt{(1 + x) (1 - x)} (- \sqrt{(1 + x) (1 - x)})$ .

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Step 6.2.1

Reorder the factors in the terms $x (- \sqrt{(1 + x) (1 - x)})$ and $\sqrt{(1 + x) (1 - x)} x$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x \cdot x - x \sqrt{(1 + x) (1 - x)} + x \sqrt{(1 + x) (1 - x)} + \sqrt{(1 + x) (1 - x)} (- \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.2.2

Add $- x \sqrt{(1 + x) (1 - x)}$ and $x \sqrt{(1 + x) (1 - x)}$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x \cdot x + 0 + \sqrt{(1 + x) (1 - x)} (- \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.2.3

Add $x \cdot x$ and $0$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x \cdot x + \sqrt{(1 + x) (1 - x)} (- \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.3

Simplify each term.

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Step 6.3.1

Multiply $x$ by $x$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} + \sqrt{(1 + x) (1 - x)} (- \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.3.2

Rewrite using the commutative property of multiplication.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - \sqrt{(1 + x) (1 - x)} \sqrt{(1 + x) (1 - x)}}{x^{2}}}$

Step 6.3.3

Multiply $- \sqrt{(1 + x) (1 - x)} \sqrt{(1 + x) (1 - x)}$ .

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Step 6.3.3.1

Raise $\sqrt{(1 + x) (1 - x)}$ to the power of $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - ({\sqrt{(1 + x) (1 - x)}}^{1} \sqrt{(1 + x) (1 - x)})}{x^{2}}}$

Step 6.3.3.2

Raise $\sqrt{(1 + x) (1 - x)}$ to the power of $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - ({\sqrt{(1 + x) (1 - x)}}^{1} {\sqrt{(1 + x) (1 - x)}}^{1})}{x^{2}}}$

Step 6.3.3.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {\sqrt{(1 + x) (1 - x)}}^{1 + 1}}{x^{2}}}$

Step 6.3.3.4

Add $1$ and $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {\sqrt{(1 + x) (1 - x)}}^{2}}{x^{2}}}$

Step 6.3.4

Rewrite ${\sqrt{(1 + x) (1 - x)}}^{2}$ as $(1 + x) (1 - x)$ .

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Step 6.3.4.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{(1 + x) (1 - x)}$ as ${((1 + x) (1 - x))}^{\frac{1}{2}}$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {({((1 + x) (1 - x))}^{\frac{1}{2}})}^{2}}{x^{2}}}$

Step 6.3.4.2

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {((1 + x) (1 - x))}^{\frac{1}{2} \cdot 2}}{x^{2}}}$

Step 6.3.4.3

Combine $\frac{1}{2}$ and $2$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {((1 + x) (1 - x))}^{\frac{2}{2}}}{x^{2}}}$

Step 6.3.4.4

Cancel the common factor of $2$ .

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Step 6.3.4.4.1

Cancel the common factor.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {((1 + x) (1 - x))}^{\frac{2}{2}}}{x^{2}}}$

Step 6.3.4.4.2

Rewrite the expression.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - {((1 + x) (1 - x))}^{1}}{x^{2}}}$

Step 6.3.4.5

Simplify.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - ((1 + x) (1 - x))}{x^{2}}}$

Step 6.3.5

Expand $(1 + x) (1 - x)$ using the FOIL Method.

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Step 6.3.5.1

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 (1 - x) + x (1 - x))}{x^{2}}}$

Step 6.3.5.2

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 \cdot 1 + 1 (- x) + x (1 - x))}{x^{2}}}$

Step 6.3.5.3

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 \cdot 1 + 1 (- x) + x \cdot 1 + x (- x))}{x^{2}}}$

Step 6.3.6

Simplify and combine like terms.

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Step 6.3.6.1

Simplify each term.

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Step 6.3.6.1.1

Multiply $1$ by $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 + 1 (- x) + x \cdot 1 + x (- x))}{x^{2}}}$

Step 6.3.6.1.2

Multiply $- x$ by $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 - x + x \cdot 1 + x (- x))}{x^{2}}}$

Step 6.3.6.1.3

Multiply $x$ by $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 - x + x + x (- x))}{x^{2}}}$

Step 6.3.6.1.4

Rewrite using the commutative property of multiplication.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 - x + x - x \cdot x)}{x^{2}}}$

Step 6.3.6.1.5

Multiply $x$ by $x$ by adding the exponents.

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Step 6.3.6.1.5.1

Move $x$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 - x + x - (x \cdot x))}{x^{2}}}$

Step 6.3.6.1.5.2

Multiply $x$ by $x$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 - x + x - x^{2})}{x^{2}}}$

Step 6.3.6.2

Add $- x$ and $x$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 + 0 - x^{2})}{x^{2}}}$

Step 6.3.6.3

Add $1$ and $0$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - (1 - x^{2})}{x^{2}}}$

Step 6.3.7

Apply the distributive property.

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - 1 \cdot 1 - - x^{2}}{x^{2}}}$

Step 6.3.8

Multiply $- 1$ by $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - 1 - - x^{2}}{x^{2}}}$

Step 6.3.9

Multiply $- - x^{2}$ .

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Step 6.3.9.1

Multiply $- 1$ by $- 1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - 1 + 1 x^{2}}{x^{2}}}$

Step 6.3.9.2

Multiply $x^{2}$ by $1$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{x^{2} - 1 + x^{2}}{x^{2}}}$

Step 6.4

Add $x^{2}$ and $x^{2}$ .

$\frac{\frac{2 \sqrt{(1 + x) (1 - x)}}{x}}{\frac{2 x^{2} - 1}{x^{2}}}$

Step 7

Multiply the numerator by the reciprocal of the denominator.

$\frac{2 \sqrt{(1 + x) (1 - x)}}{x} \cdot \frac{x^{2}}{2 x^{2} - 1}$

Step 8

Cancel the common factor of $x$ .

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Step 8.1

Factor $x$ out of $x^{2}$ .

$\frac{2 \sqrt{(1 + x) (1 - x)}}{x} \cdot \frac{x \cdot x}{2 x^{2} - 1}$

Step 8.2

Cancel the common factor.

$\frac{2 \sqrt{(1 + x) (1 - x)}}{x} \cdot \frac{x \cdot x}{2 x^{2} - 1}$

Step 8.3

Rewrite the expression.

$2 \sqrt{(1 + x) (1 - x)} \frac{x}{2 x^{2} - 1}$

Step 9

Combine $\frac{x}{2 x^{2} - 1}$ and $2$ .

$\frac{x \cdot 2}{2 x^{2} - 1} \sqrt{(1 + x) (1 - x)}$

Step 10

Combine $\frac{x \cdot 2}{2 x^{2} - 1}$ and $\sqrt{(1 + x) (1 - x)}$ .

$\frac{x \cdot 2 \sqrt{(1 + x) (1 - x)}}{2 x^{2} - 1}$

Step 11

Move $2$ to the left of $x$ .

$\frac{2 x \sqrt{(1 + x) (1 - x)}}{2 x^{2} - 1}$