As Agent Trigonometry you are given this clue: . How could you simplify this expression to make solving your case easier?

### Guidance

We can also use the sum and difference formulas to simplify trigonometric expressions.

#### Example A

The and . is in the quadrant and is in the . Find .

**
Solution:
**
First, we need to find
and
. Using the Pythagorean Theorem, missing lengths are 4 and 5, respectively. So,
because it is in the
quadrant and
. Now, use the appropriate formulas.

#### Example B

Using the information from Example A, find .

**
Solution:
**
From the cosine and sine of
and
, we know that
and
.

#### Example C

Simplify .

**
Solution:
**
Expand this using the difference formula and then simplify.

**
Concept Problem Revisit
**
You can expand the expression using the difference formula and then simplify.

### Guided Practice

1. Using the information from Example A, find .

2. Simplify .

**
Answers
**

1.

2.

### Practice

and . Find the exact trig values of:

Simplify the following expressions.

Determine if the following trig statements are true or false.