Precalculus by Richard Wright

When a person looks at their reflection in a mirror or still water, they see themselves. The image on both sides is the same. They can move and the reflection moves in the same way. The reflection always shows the person's identity. In math, an identity is an equation that is always the same value on both sides of the equation no matter the input.

5-01 Fundamental Trigonometric Identities Part A

5-02 Fundamental Trigonometric Identities Part B

5-03 Verify Trigonometric Identities

5-04 Solve Trigonometric Equations