Precalculus : Sum and Difference Identities For Cosine

Study concepts, example questions & explanations for Precalculus

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Example Questions

Example Question #4 : Sum And Difference Identities

Use the sum or difference identity to find the exact value: 

Possible Answers:

Correct answer:

Explanation:

Using the identity, we can break up the 255 into and then solve:   

Example Question #1 : Sum And Difference Identities

Is the following equation an identity? 

Possible Answers:

It cannot be determined from the given information.

Yes it is an identity.

No it is not an identity.

Correct answer:

No it is not an identity.

Explanation:

and due to this inequality, this is not an identity

Example Question #2 : Sum And Difference Identities

Use the sum or difference identity to find the exact value: 

Possible Answers:

Correct answer:

Explanation:

Using the identity, we can break up the  into  and then solve:  and so the correct answer is .

Example Question #2 : Sum And Difference Identities

Is the following equation an identity?

Possible Answers:

The answer cannot be determined from the information provided.

No it is not an identity

Yes it is an identity

Correct answer:

No it is not an identity

Explanation:

Due to this inequality, this is not an identity.

Example Question #2 : Trigonometric Identities

Use the sum or difference identity to find the exact value of .

Possible Answers:

Correct answer:

Explanation:

Here we break up the  into  and solve using the sin identity:  and so here the credited answer is .

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