Trigonometry Examples

$y = \frac{1}{2} \cdot \cos (\frac{x}{2} + 270)$

Step 1

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

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

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

$c = - 270$

$d = 0$

Step 2

Find the amplitude $| a |$ .

Amplitude: $\frac{1}{2}$

Step 3

Find the period of $\frac{\cos (\frac{x}{2} + 270)}{2}$ .

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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: $\frac{- 270}{\frac{1}{2}}$

Step 4.3

Multiply the numerator by the reciprocal of the denominator.

Phase Shift: $- 270 \cdot 2$

Step 4.4

Multiply $- 270$ by $2$ .

Phase Shift: $- 540$

Step 5

List the properties of the trigonometric function.

Amplitude: $\frac{1}{2}$

Period: $4 π$

Phase Shift: $- 540$ ( $540$ to the left)

Vertical Shift: None

Step 6