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Find the period and amplitude. $$y=\frac{5}{2} \cos \frac{x}{4}$$

Short Answer

Expert verified
The amplitude of the given function is \(\frac{5}{2}\) and the period is 8\pi.

Step by step solution

01

Identifying the amplitude and B value of the cosine function

In the function \(y=\frac{5}{2} \cos \frac{x}{4}\), the amplitude A is the absolute value of the coefficient before the cosine function, and B is the coefficient of x inside the cosine function. Therefore, A = \(\frac{5}{2}\) and B = \(\frac{1}{4}\).
02

Finding the amplitude

The amplitude of the function is equal to the absolute value of A which is \(\frac{5}{2}\).
03

Finding the period

The period of the function is found using the formula \( \frac{2\pi}{B} \). After substituting B = \(\frac{1}{4}\) into the formula, you get the period as 8\pi.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Amplitude
Amplitude in trigonometric functions determines how tall the wave peaks are from the midpoint, which is often the horizontal axis if no vertical shifts are involved. In simple terms, amplitude tells us how high and low the graph of the function goes.For the function \(y = \frac{5}{2} \cos \frac{x}{4}\), amplitude is determined by the coefficient in front of the cosine function.- To find amplitude, take the absolute value of this coefficient.- In our example, the coefficient is \(\frac{5}{2}\).- Therefore, the amplitude is \(\frac{5}{2}\).Remember, amplitude will always be a positive number because it represents a distance. Whether the graph stretches above or below its middle point, it extends equally in both directions.
Period
The period of a trigonometric function is the length of one complete cycle of the wave. It tells you how much you have to move along the x-axis before the wave pattern repeats.To determine the period of a cosine function, use the formula:- \[ \text{Period} = \frac{2\pi}{B} \]where \(B\) is the coefficient of \(x\) inside the cosine.In our function \(y = \frac{5}{2} \cos \frac{x}{4}\):- The coefficient \(B = \frac{1}{4}\).- Plugging \(B\) into the period formula gives:- \[ \frac{2\pi}{\frac{1}{4}} = 8\pi \]So, the period of this function is \(8\pi\). This means the cosine wave takes a distance of \(8\pi\) to start repeating its shape.
Cosine Function
The cosine function, part of the family of trigonometric functions, is commonly used in scenarios involving waves and circular motion. The basic form is \(y = A \cos(Bx + C) + D\), where each letter represents a transformation or characteristic:- \(A\): Amplitude, changing the height of the wave as previously discussed.- \(B\): Affects the period of the wave.- \(C\): Changes the horizontal phase shift, moving the graph along the x-axis.- \(D\): Adjusts the vertical shift, moving the graph up or down.The function \(y = \frac{5}{2} \cos \frac{x}{4}\) is a transformed version of the basic cosine wave. Here, \(A = \frac{5}{2}\) makes peaks and valleys extend \(\frac{5}{2}\) units vertically from the middle line. \(B = \frac{1}{4}\) increases the period to \(8\pi\), meaning the full wave cycle occurs more slowly.

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Most popular questions from this chapter

Distance A plane flying at an altitude of 7 miles above a radar antenna will pass directly over the radar antenna (see figure). Let \(d\) be the ground distance from the antenna to the point directly under the plane and let \(x\) be the angle of elevation to the plane from the antenna. (d is positive as the plane approaches the antenna.) Write \(d\) as a function of \(x\) and graph the function over the interval \(0 < x < \pi\).

Write an equation for the function that is described by the given characteristics. A cosine curve with a period of \(4 \pi,\) an amplitude of 3 a right phase shift of \(\pi / 2,\) and a vertical translation up 2 units

Determine whether the statement is true or false. Justify your answer. $$\tan \frac{5 \pi}{4}=1 \rightarrow \arctan 1=\frac{5 \pi}{4}$$

Define the inverse secant function by restricting the domain of the secant function to the intervals \([0, \pi / 2)\) and \((\pi / 2, \pi],\) and sketch the graph of the inverse trigonometric function.

The table shows the average sales \(S\) (in millions of dollars) of an outerwear manufacturer for each month \(t,\) where \(t=1\) represents January. $$\begin{array}{|l|c|c|c|c|c|c|}\hline \text { Time, } t & 1 & 2 & 3 & 4 & 5 & 6 \\\\\hline \text { Sales, } S & 13.46 &11.15 & 8.00 & 4.85 & 2.54 & 1.70 \\\\\hline\end{array}$$ $$\begin{array}{|l|c|c|c|c|c|c|}\hline \text { Time, } t & 7 & 8 & 9 & 10 & 11 & 12 \\\\\hline \text { Sales, } S & 2.54 & 4.85 & 8.00 & 11.15 & 13.46 & 14.30 \\\\\hline\end{array}$$ (a) Create a scatter plot of the data. (b) Find a trigonometric model that fits the data. Graph the model with your scatter plot. How well does the model fit the data? (c) What is the period of the model? Do you think it is reasonable given the context? Explain your reasoning. (d) Interpret the meaning of the model's amplitude in the context of the problem.

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