Trigonometry : Trigonometric Graphs

Study concepts, example questions & explanations for Trigonometry

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Example Questions

Example Question #11 : Trigonometric Graphs

Which of the following is the correct definition of a phase shift?

Possible Answers:

The distance a function is shifted vertically from the general position

The distance a function is shifted horizontally from the general position

A measure of the length of a function between vertical asymptotes

The distance a function is shifted diagonally from the general position

Correct answer:

The distance a function is shifted horizontally from the general position

Explanation:

Take the function  for example.  The graph for is

 

 

If we were to change the function to , our phase shift is .  This means we need to shift our entire graph  units to the left.

 

 

Our new graph  is the following

 

 

 

Example Question #12 : Trigonometric Graphs

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

Possible Answers:

Correct answer:

Explanation:

The general form for the secant transformation equation is  represents the phase shift of the function.  When considering  we see that .  So our phase shift is  and we would shift this function  units to the left of the original secant function’s graph.

 

 

Example Question #13 : Trigonometric Graphs

True or False: If the function  has a phase shift of , then the graph will not be changed.

Possible Answers:

False

True 

Correct answer:

True 

Explanation:

This is true because the graph  has a period of , meaning it repeats itself every  units.  So if  has a phase shift of any multiple of , then it will just overlay the original graph.  This is shown below.  In orange is the graph of and in purple is the graph of  .

 

 

 

Example Question #14 : Trigonometric Graphs

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

Possible Answers:

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Screen shot 2020 08 27 at 2.35.10 pm

Screen shot 2020 08 27 at 2.36.46 pm

Screen shot 2020 08 27 at 2.35.20 pm

Correct answer:

Screen shot 2020 08 27 at 2.35.20 pm

Explanation:

Start this problem by graphing the function of tangent.

Screen shot 2020 08 27 at 2.35.10 pm

Now we need to shift this graph  to the right.

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This gives us our answer

 Screen shot 2020 08 27 at 2.35.20 pm

Example Question #1 : Phase Shifts

True or False: The function  has a phase shift of  .

Possible Answers:

True 

False

Correct answer:

False

Explanation:

The form of the general cosecant function is .  So if we have  then , which represents the phase shift, is equal to .  This gives us a phase shift of .

Example Question #61 : Trigonometric Functions And Graphs

Which of the following is the phase shift of the function ?

Possible Answers:

Correct answer:

Explanation:

The general form of the cotangent function is .  So first we need to get   into the form .

 


From this we see that  giving us our answer.

Example Question #1 : Graphing Sine And Cosine

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

Possible Answers:

Correct answer:

Explanation:

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 .

Example Question #1 : Graphing Sine And Cosine

This is the graph of what function?

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Possible Answers:

Correct answer:

Explanation:

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

Example Question #1 : Graphing Sine And Cosine

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

Possible Answers:

Correct answer:

Explanation:

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

Example Question #1 : Graphing Sine And Cosine

Which graph correctly illustrates the given equation?

Possible Answers:

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Correct answer:

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Explanation:

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:

Screenshot__2_

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