### Trigonometry

Topics within Trigonometry

## Identities

Trigonometric identities are the most important part of the entire subject - if you read only one page from this course, it should be this one.

We're going to start exploring the following rectangle:

Copy the diagram down, and try to fill in all the blanks in the order below.

1. #### Angles

$\displaystyle{m\angle BDC = }$

$\displaystyle{m\angle ABF}=$

2. #### Sides

$\displaystyle{AF}=$

$\displaystyle{AB}=$

$\displaystyle{BD}=$

$\displaystyle{FD}=$

$\displaystyle{BC}=$

$\displaystyle{CD}=$

$\displaystyle{DE}=$

$\displaystyle{FE}=$

3. Express AB and AF in terms of other sides of the rectangle. Then, substitute the values above to see the trigonometric identities.