Trigonometric Graphs - Trigonometry

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Question

Let be a function defined as follows:

The 4 in the function above affects what attribute of the graph of ?

Answer

The period of the function is indicated by the coefficient in front of ; here the period is unchanged.

The amplitude of the function is given by the coefficient in front of the ; here the amplitude is -1.

The phase shift is given by the value being added or subtracted inside the function; here the shift is units to the right.

The only unexamined attribute of the graph is the vertical shift, so 4 is the vertical shift of the graph. A vertical shift of 4 means that the entire graph of the function will be moved up four units (in the positive y-direction).

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Question

Let be a function defined as follows:

What is the vertical shift in this function?

Answer

The period of the function is indicated by the coefficient in front of ; here the period is unchanged.

The amplitude of the function is given by the coefficient in front of the ; here the amplitude is 3.

The phase shift is given by the value being added or subtracted inside the cosine function; here the shift is units to the right.

The only unexamined attribute of the graph is the vertical shift, so -3 is the vertical shift of the graph. A vertical shift of -3 means that the entire graph of the function will be moved down three units (in the negative y-direction).

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Question

This graph shows a translated cosine function. Which of the following could be the equation of this graph?

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Answer

The correct answer is . There are no sign changes with vertical shifts; in other words, when the function includes , it directly translates to moving up three units. If you thought the answer was , you may have spotted the y-intercept at and jumped to this answer. However, recall that the y-intercept of a regular function is at the point . Beginning at and ending at corresponds to a vertical shift of 3 units.

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Question

The graph below shows a translated sine function. Which of the following functions could be shown by this graph?

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Answer

A normal graph has its y-intercept at . This graph has its y-intercept at . Therefore, the graph was shifted down three units. Therefore the function of this graph is .

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Question

Consider the function . What is the vertical shift of this function?

Answer

The general form for the secant transformation equation is . represents the phase shift of the function. When considering we see that , so our vertical shift is and we would shift this function units up from the original secant function’s graph.

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Question

Which of the following is the graph of with a vertical shift of ?

Answer

The graph of with a vertical shift of is shown below. This can also be expressed as .

Secx  3

Here is a graph that shows both and , so that you can see the "before" and "after." The original function is in blue and the translated function is in purple.

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The graphs of the incorrect answer choices are (no vertical shift applied), (shifted upwards instead of downwards), (amplitude modified, and shifted upwards instead of downwards), and (shifted downwards 3 units, but this is not the correct original graph of simply since the amplitude was modified.)

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Question

Which of the following graphs shows one of the original six trigonometric functions with a vertical shift of applied?

Answer

We are looking for an answer choice that has one of the six trigonometric functions, as well as that function shifted up 3 units. The only answer choice that displays that is this graph of (purple) and (blue).

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The incorrect answers depict and , and , and and .

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Question

This is the graph of what function of x?

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Answer

is shown in red, and is shown in blue.

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Question

Give the equation of the following graph.

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Answer

Looking at our graph, we can tell that the period is . Using the formula

where is the coefficient of and is the period, we can calculate

This eliminates one answer choice. We then retrun to our graph and see that the amplitude is 3. Remembering that the amplitude is the number in front of the function, we can eliminate two more choices.

We then examine our graph and realize it contains the point . Plugging 0 into our two remaining choices, we can determine which one gives us 4 for a result.

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Question

Which of the following is the graph of ?

Answer

In order to graph , recall that . First consider the graph .

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Now anywhere this graph crosses the x-axis a vertical asymptote will form for the graph because the denominator of will be equal to zero and the function will be undefined. At each maximum and minimum of , the graph of will invert at that point.

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And then we are left with the graph of .

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Question

Considering the general form of the cosecant transformation function , what does each letter, (A, B, C, and D) correspond to?

Answer

Since cosecant is a reciprocal of sine, it uses the same general formula of the sine function with the letters corresponding to the same transformations. Note that while A does correspond to amplitude, the cosecant function extends infinitely upwards and downwards so there is no amplitude for the graphs.

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Question

Which of the following is the graph of ?

Answer

Knowing that the graph of is

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we can use the general form of the cosecant transformation equation, , and apply these transformations. We can ignore because in this case . In this case and so our period is:

Period =

Period =

Period =

is the normal period for cosecant graphs and so we do not have to worry about lengthening or shortening the period. and so we need to apply a phase shift of . This will cause our graph to shift left a total of units.

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Lastly, we must apply the transformation for , so we will have an upward vertical shift of 1 unit.

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The application of these transformations leaves us with our graph of .

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Question

Which of the following is the graph for ?

Answer

In order to understand the graph of secant, recall that . First consider the graph of .

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Anywhere this graph crosses the x-axis a vertical asymptote will form for the graph because the denominator of will be equal to zero and the function will be undefined. At each maximum and minimum of , the graph of will invert at that point.

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And then we are left with the graph .

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Question

True or False: Amplitude must be considered when graphing the transformation of a secant graph.

Answer

When looking at the graph of , it extends infinitely upwards and downwards from each local maximum and minimum. This will be true for all transformed secant graphs as well. Due to this, there is no amplitude for secant graphs. However, secant is the reciprocal of cosine graphs which do rely on amplitude for transformations. For this reason amplitude must be considered as a vertical shift.

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Question

Which of the following is the graph of ?

Answer

Knowing that the general form of the graph is:

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We can use the general form of the cosecant transformation equation, , and apply these transformations. because secant graphs extend infinitely upwards and downwards and does not have an amplitude, we must think of the secant graph being a reciprocal of the cosine graph. So we will consider for cosine.

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We will shift our secant graph to invert at the maximums and minimums of the cosine graph.

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Next, we will factor in order to get our equation into the form .

And so . We can now solve for our period,

Period =

Period =

Period =

This shortens our original period of to .

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Now we must consider . This will give us a phase shift of units to the left. Since our period has also been shortened this does not change the graph visually. in this case so we do not need to consider a vertical shift.

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And we are left with the graph of .

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Question

This is the graph of what function?

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Answer

The amplitude of the sine function is increased by 3, so this is the coefficient for . The +2 shows that the origin of the function is now at instead of

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Question

The function shown below has an amplitude of ___________ and a period of _________.

Answer

The amplitude is always a positive number and is given by the number in front of the trigonometric function. In this case, the amplitude is 4. The period is given by , where b is the number in front of x. In this case, the period is .

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Question

Which of the following graphs does not have a -intercept at ?

Answer

The y-intercept is the value of y when .

Recall that cosine is the value of the unit circle. Thus, , so it works.

Secant is the reciprocal of cosine, so it also works.

Also recall that . Thus, the only answer which is not equivalent is .

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Question

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What is an equation for the above function, enlarged below?

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Answer

The amplitude of a sinusoidal function is unless amplified by a constant in front of the equation. In this case, the amplitude is , so the front constant is .

The graph moves through the origin, so it is either a sine or a shifted cosine graph.

It repeats once in every , as opposed to the usual , so the period is doubled, the constant next to the variable is .

The only answer in which both the correct amplitude and period is found is:

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Question

Which graph correctly illustrates the given equation?

Answer

The simplest way to solve a problem like this is to determine where a particular point on the graph would lie and then compare that to our answer choices. We should first find the y-value when the x-value is equal to zero. We will start by substituting zero in for the x-variable in our equation.

Now that we have calculated the y-value we know that the correct graph must have the following point:

Unfortunately, two of our graph choices include this point; thus, we need to pick a second point.

Let's find the y-value when the x-variable equals the following:

We will begin by substituting this into our original equation.

Now we need to investigate the two remaining choices for the following point:

Unfortunately, both of our remaining graphs have this point as well; therefore, we need to pick another x-value. Suppose the x-variable equals the following:

Now, we must substitute this value into our given equation.

Now, we can look for the graph with the following point:

We have narrowed in on our final answer; thus, the following graph is correct:

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