### All Precalculus Resources

## Example Questions

### Example Question #1 : Sum And Difference Identities

According to the trigonometric identities,

**Possible Answers:**

**Correct answer:**

The trigonometric identity , is an important identity to memorize.

Some other identities that are important to know are:

### Example Question #2 : Sum And Difference Identities

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

**Possible Answers:**

**Correct answer:**

Again, here we break up the 165 into and solve using the sin identity:

### 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.

and so this is again not an identity

### Example Question #1 : Sum And Difference Identities

Is the following equation an identity? ?

**Possible Answers:**

Yes it is an identity

The question cannot be answered based on the information provided.

No it is not an identity

### Example Question #5 : Sum And Difference Identities

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

**Possible Answers:**

### Example Question #1 : Sum And Difference Identities

Is the following equation an identity?

**Possible Answers:**

No it is not an identity.

It cannot be determined from the given information.

Yes it is an identity.

**Correct answer:**

No it is not an identity.

and due to this inequality, this is not an identity

### Example Question #7 : Sum And Difference Identities

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

**Possible Answers:**

**Correct answer:**

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

### Example Question #1 : Sum And Difference Identities

**Possible Answers:**

The answer cannot be determined from the information provided.

Yes it is an identity

No it is not an identity

### Example Question #9 : Sum And Difference Identities

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

**Correct answer:**

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

### Example Question #10 : Sum And Difference Identities

Evaluate the exact value of:

**Possible Answers:**

**Correct answer:**

In order to solve , two special angles will need to be used to solve for the exact values.

The angles chosen are and degrees, since:

Write the formula for the cosine additive identity.

Substitute the known variables.