### All Precalculus Resources

## Example Questions

### Example Question #242 : Pre Calculus

Find the exact value

.

**Possible Answers:**

**Correct answer:**

Explanation:

By the double angle formula

### Example Question #41 : Trigonometric Identities

Find the exact value

.

**Possible Answers:**

**Correct answer:**

Explanation:

By the double angle formula

### Example Question #1 : Double And Half Angle Identities

Find the exact value

.

**Possible Answers:**

**Correct answer:**

Explanation:

By the double-angula formula for cosine

For this problem

### Example Question #1 : Double Angle Identities

Find the exact value

.

**Possible Answers:**

**Correct answer:**

Explanation:

By the double-angle formula for the sine function

we have

thus the double angle formula becomes,

### Example Question #2 : Double Angle Identities

If , which of the following best represents ?

**Possible Answers:**

**Correct answer:**

Explanation:

The expression is a double angle identity that can also be rewritten as:

Replace the value of theta for .

The correct answer is:

### Example Question #1 : Double Angle Identities

Which expression is equivalent to ?

**Possible Answers:**

**Correct answer:**

Explanation:

The relevant trigonometric identity is:

In this case, "u" is since .

The only one that actually follows this is