Trigonometry Examples

$(\frac{- \sqrt{3}}{2}, - \frac{1}{2})$

Step 1

To find the $\cos (θ)$ between the x-axis and the line between the points $(0, 0)$ and $(\frac{- \sqrt{3}}{2}, - \frac{1}{2})$ , draw the triangle between the three points $(0, 0)$ , $(\frac{- \sqrt{3}}{2}, 0)$ , and $(\frac{- \sqrt{3}}{2}, - \frac{1}{2})$ .

Opposite : $- \frac{1}{2}$

Adjacent : $\frac{- \sqrt{3}}{2}$

Step 2

Find the hypotenuse using Pythagorean theorem $c = \sqrt{a^{2} + b^{2}}$ .

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Step 2.1

Move the negative in front of the fraction.

$\sqrt{{(- \frac{\sqrt{3}}{2})}^{2} + {(- \frac{1}{2})}^{2}}$

Step 2.2

Use the power rule ${(a b)}^{n} = a^{n} b^{n}$ to distribute the exponent.

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Step 2.2.1

Apply the product rule to $- \frac{\sqrt{3}}{2}$ .

$\sqrt{{(- 1)}^{2} {(\frac{\sqrt{3}}{2})}^{2} + {(- \frac{1}{2})}^{2}}$

Step 2.2.2

Apply the product rule to $\frac{\sqrt{3}}{2}$ .

$\sqrt{{(- 1)}^{2} \frac{{\sqrt{3}}^{2}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.3

Simplify the expression.

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Step 2.3.1

Raise $- 1$ to the power of $2$ .

$\sqrt{1 \frac{{\sqrt{3}}^{2}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.3.2

Multiply $\frac{{\sqrt{3}}^{2}}{2^{2}}$ by $1$ .

$\sqrt{\frac{{\sqrt{3}}^{2}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.4

Rewrite ${\sqrt{3}}^{2}$ as $3$ .

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Step 2.4.1

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{3}$ as $3^{\frac{1}{2}}$ .

$\sqrt{\frac{{(3^{\frac{1}{2}})}^{2}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.4.2

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

$\sqrt{\frac{3^{\frac{1}{2} \cdot 2}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.4.3

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

$\sqrt{\frac{3^{\frac{2}{2}}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.4.4

Cancel the common factor of $2$ .

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Step 2.4.4.1

Cancel the common factor.

$\sqrt{\frac{3^{\frac{2}{2}}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.4.4.2

Rewrite the expression.

$\sqrt{\frac{3^{1}}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.4.5

Evaluate the exponent.

$\sqrt{\frac{3}{2^{2}} + {(- \frac{1}{2})}^{2}}$

Step 2.5

Raise $2$ to the power of $2$ .

$\sqrt{\frac{3}{4} + {(- \frac{1}{2})}^{2}}$

Step 2.6

Use the power rule ${(a b)}^{n} = a^{n} b^{n}$ to distribute the exponent.

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Step 2.6.1

Apply the product rule to $- \frac{1}{2}$ .

$\sqrt{\frac{3}{4} + {(- 1)}^{2} {(\frac{1}{2})}^{2}}$

Step 2.6.2

Apply the product rule to $\frac{1}{2}$ .

$\sqrt{\frac{3}{4} + {(- 1)}^{2} \frac{1^{2}}{2^{2}}}$

Step 2.7

Raise $- 1$ to the power of $2$ .

$\sqrt{\frac{3}{4} + 1 \frac{1^{2}}{2^{2}}}$

Step 2.8

Multiply $\frac{1^{2}}{2^{2}}$ by $1$ .

$\sqrt{\frac{3}{4} + \frac{1^{2}}{2^{2}}}$

Step 2.9

One to any power is one.

$\sqrt{\frac{3}{4} + \frac{1}{2^{2}}}$

Step 2.10

Raise $2$ to the power of $2$ .

$\sqrt{\frac{3}{4} + \frac{1}{4}}$

Step 2.11

Combine the numerators over the common denominator.

$\sqrt{\frac{3 + 1}{4}}$

Step 2.12

Add $3$ and $1$ .

$\sqrt{\frac{4}{4}}$

Step 2.13

Divide $4$ by $4$ .

$\sqrt{1}$

Step 2.14

Any root of $1$ is $1$ .

$1$

Step 3

$\cos (θ) = \frac{Adjacent}{Hypotenuse}$ therefore $\cos (θ) = \frac{\frac{- \sqrt{3}}{2}}{1}$ .

$\frac{\frac{- \sqrt{3}}{2}}{1}$

Step 4

Simplify $\cos (θ)$ .

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Step 4.1

Divide $\frac{- \sqrt{3}}{2}$ by $1$ .

$\cos (θ) = \frac{- \sqrt{3}}{2}$

Step 4.2

Move the negative in front of the fraction.

$\cos (θ) = - \frac{\sqrt{3}}{2}$

Step 5

Approximate the result.

$\cos (θ) = - \frac{\sqrt{3}}{2} \approx - 0.8660254$