Trigonometry Examples

$3 + \sqrt{3} i$

Step 1

This is the trigonometric form of a complex number where $| z |$ is the modulus and $θ$ is the angle created on the complex plane.

$z = a + b i = | z | (\cos (θ) + i \sin (θ))$

Step 2

The modulus of a complex number is the distance from the origin on the complex plane.

$| z | = \sqrt{a^{2} + b^{2}}$ where $z = a + b i$

Step 3

Substitute the actual values of $a = 3$ and $b = \sqrt{3}$ .

$| z | = \sqrt{{(\sqrt{3})}^{2} + 3^{2}}$

Step 4

Find $| z |$ .

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Step 4.1

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

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Step 4.1.1

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

$| z | = \sqrt{{(3^{\frac{1}{2}})}^{2} + 3^{2}}$

Step 4.1.2

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

$| z | = \sqrt{3^{\frac{1}{2} \cdot 2} + 3^{2}}$

Step 4.1.3

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

$| z | = \sqrt{3^{\frac{2}{2}} + 3^{2}}$

Step 4.1.4

Cancel the common factor of $2$ .

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Step 4.1.4.1

Cancel the common factor.

$| z | = \sqrt{3^{\frac{2}{2}} + 3^{2}}$

Step 4.1.4.2

Rewrite the expression.

$| z | = \sqrt{3 + 3^{2}}$

Step 4.1.5

Evaluate the exponent.

$| z | = \sqrt{3 + 3^{2}}$

Step 4.2

Simplify the expression.

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Step 4.2.1

Raise $3$ to the power of $2$ .

$| z | = \sqrt{3 + 9}$

Step 4.2.2

Add $3$ and $9$ .

$| z | = \sqrt{12}$

Step 4.3

Rewrite $12$ as $2^{2} \cdot 3$ .

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Step 4.3.1

Factor $4$ out of $12$ .

$| z | = \sqrt{4 (3)}$

Step 4.3.2

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

$| z | = \sqrt{2^{2} \cdot 3}$

Step 4.4

Pull terms out from under the radical.

$| z | = 2 \sqrt{3}$

Step 5

The angle of the point on the complex plane is the inverse tangent of the complex portion over the real portion.

$θ = \arctan (\frac{\sqrt{3}}{3})$

Step 6

Since inverse tangent of $\frac{\sqrt{3}}{3}$ produces an angle in the first quadrant, the value of the angle is $\frac{π}{6}$ .

$θ = \frac{π}{6}$

Step 7

Substitute the values of $θ = \frac{π}{6}$ and $| z | = 2 \sqrt{3}$ .

$2 \sqrt{3} (\cos (\frac{π}{6}) + i \sin (\frac{π}{6}))$