Trigonometry : Trigonometry

Study concepts, example questions & explanations for Trigonometry

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Example Questions

Example Question #1 : Product Of Sines And Cosines

Use the product of cosines to evaluate 

Possible Answers:

Correct answer:

Explanation:

We are using the identity .  We will let  and .

 

 

 

Example Question #1 : Product Of Sines And Cosines

Use the product of sines to evaluate  where 

Possible Answers:

Correct answer:

Explanation:

The formula for the product of sines is .  We will let  and .

 

 

 

Example Question #1 : Product Of Sines And Cosines

True or False: All of the product-to-sum identities can be obtained from the sum-to-product identities

Possible Answers:

False

True 

Correct answer:

True 

Explanation:

All of these identities are able to be obtained by the sum-to-product identities by either adding or subtracting two of the sum identities and canceling terms.  Through some algebra and manipulation, you are able to derive each product identity.

Example Question #2 : Product Of Sines And Cosines

Use the product of sine and cosine to evaluate .

Possible Answers:

Correct answer:

Explanation:

The identity that we will need to utilize to solve this problem is .  We will let  and  .

 

 

 

Example Question #2 : Product Of Sines And Cosines

Use the product of cosines to evaluate .  Keep your answer in terms of .

Possible Answers:

Correct answer:

Explanation:

The identity we will be using is .  We will let  and .

Example Question #2 : Product Of Sines And Cosines

Use the product of sines to evaluate .

Possible Answers:

Correct answer:

Explanation:

The identity that we will need to use is .  We will let  and .

 

 

 

Example Question #1 : Graphs Of Inverse Trigonometric Functions

True or False: The inverse of the function  is also a function.

Possible Answers:

True

False

Correct answer:

False

Explanation:

 Consider the graph of the function .  It passes the vertical line test, that is if a vertical line is drawn anywhere on the graph it only passes through a single point of the function. This means that  is a function.

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Now, for its inverse to also be a function it must pass the horizontal line test. This means that if a horizontal line is drawn anywhere on the graph it will only pass through one point.

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This is not true, and we can also see that if we graph the inverse of  () that this does not pass the vertical line test and therefore is not a function.  If you wish to graph the inverse of , then you must restrict the domain so that your graph will pass the vertical line test.

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Example Question #1 : Graphs Of Inverse Trigonometric Functions

Which of the following is the graph of the inverse of  with ?

Possible Answers:

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Correct answer:

Screen shot 2020 08 27 at 10.46.15 am

Explanation:

Note that the inverse of  is not , that is the reciprocal.  The inverse of  is  also written as .  The graph of  with  is as follows.

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And so the inverse of this graph must be the following with  and 

Screen shot 2020 08 27 at 10.46.15 am

Example Question #3 : Graphs Of Inverse Trigonometric Functions

Which best describes the easiest method to graph an inverse trigonometric function (or any function) based on the parent function?

Possible Answers:

The  values are swapped with  so where  for the parent function,  for the inverse function.

Let  so where  for the parent function  for the inverse function.

The  and  values are switched so where  for the parent function,  for the inverse function.

Let  so where  for the parent function,  for the inverse function.

Correct answer:

The  and  values are switched so where  for the parent function,  for the inverse function.

Explanation:

To find an inverse function you swap the and values.  Take  for example, to find the inverse we use the following method.

 

 (swap the  and  values)

(solving for )

 

 

Example Question #4 : Graphs Of Inverse Trigonometric Functions

Which of the following represents the graph of  with  ?

Possible Answers:

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Correct answer:

Screen shot 2020 08 28 at 9.01.00 am

Explanation:

 If we are looking for the graph of  with , that means this is the inverse of   with .  The graph of  with  is

Screen shot 2020 08 28 at 9.00.48 am

Switching the  and   values to graph the inverse we get the graph

Screen shot 2020 08 28 at 9.01.00 am

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