As Agent Trigonometry, you are given the following cryptic clue. How could you simplify this clue?

### Guidance

We can also use the double-angle and half-angle formulas to simplify trigonometric expressions.

#### Example A

Simplify .

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Solution:
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Use
and then factor.

#### Example B

Find the formula for .

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Solution:
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You will need to use the sum formula and the double-angle formula.

We will explore other possibilities for the because of the different formulas for in the Problem Set.

#### Example C

Verify the identity .

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Solution:
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Simplify the left-hand side use the half-angle formula.

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Concept Problem Revisit
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Use and then factor.

### Guided Practice

1. Simplify .

2. Verify .

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Answers
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1.

2.

### Practice

Simplify the following expressions.

Verify the following identities.