Trigonometry Examples

$y = - \sin (\frac{x}{2} + \frac{π}{3})$

Step 1

Use the form

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

$a = - 1$

$b = \frac{1}{2}$

$c = - \frac{π}{3}$

$d = 0$

Step 2

Find the amplitude

$| a |$ .

Amplitude:

$1$

Step 3

Find the period of

$- \sin (\frac{x}{2} + \frac{π}{3})$ .

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Step 3.1

The period of the function can be calculated using

$\frac{2 π}{| b |}$ .

$\frac{2 π}{| b |}$

Step 3.2

Replace

$b$ with

$\frac{1}{2}$ in the formula for period.

$\frac{2 π}{| \frac{1}{2} |}$

Step 3.3

$\frac{1}{2}$ is approximately

$0.5$ which is positive so remove the absolute value

$\frac{2 π}{\frac{1}{2}}$

Step 3.4

Multiply the numerator by the reciprocal of the denominator.

$2 π \cdot 2$

Step 3.5

Multiply

$2$ by

$2$ .

$4 π$

Step 4

Find the phase shift using the formula

$\frac{c}{b}$ .

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Step 4.1

The phase shift of the function can be calculated from

$\frac{c}{b}$ .

Phase Shift:

$\frac{c}{b}$

Step 4.2

Replace the values of

$c$ and

$b$ in the equation for phase shift.

Phase Shift:

$\frac{- \frac{π}{3}}{\frac{1}{2}}$

Step 4.3

Multiply the numerator by the reciprocal of the denominator.

Phase Shift:

$- \frac{π}{3} \cdot 2$

Step 4.4

Multiply

$- \frac{π}{3} \cdot 2$ .

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Step 4.4.1

Multiply

$2$ by

$- 1$ .

Phase Shift:

$- 2 \frac{π}{3}$

Step 4.4.2

Combine

$- 2$ and

$\frac{π}{3}$ .

Phase Shift:

$\frac{- 2 π}{3}$

Phase Shift:

$\frac{- 2 π}{3}$

Step 4.5

Move the negative in front of the fraction.

Phase Shift:

$- \frac{2 π}{3}$

Phase Shift:

$- \frac{2 π}{3}$

Step 5

List the properties of the trigonometric function.

Amplitude:

$1$

Period:

$4 π$

Phase Shift:

$- \frac{2 π}{3}$ (

$\frac{2 π}{3}$ to the left)

Vertical Shift: None

Step 6