![A graph of sine and cosine](./assets/graphsincos.png)

Given the above graph:
- At the origin, $sin(x) = 0$ and $cos(x) = 1$
- A full wavelength takes $2\pi$

# Manipulation
| Formula          | Movement                           |
| ---------------- | ---------------------------------- |
| $y = cos(x) - 1$ | Vertical shift down by 1           |
| $y = 2cos(x)$    | Vertical stretch by a factor of 2  |
| $y = -cos(x)$    | Flip over x axis                   |
| $y = cos(2x)$    | Horizontal shrink by a factor of 2 |
# Periodic Functions
A function is considered periodic if it repeats itself at even intervals, where each interval is a complete cycle, referred to as a *period*.


# Sinusoidal Functions
A function that has the same shape as a sine or cosine wave is known as a sinusoidal function.

There are 4 general functions:

| $$A * sin(B*x - C) + D$$ | $$ y = A * cos(B*x -c) + D$$ |
| ------------------------ | ---------------------------- |


| Variable | Meaning                                                                                       |
| -------- | --------------------------------------------------------------------------------------------- |
| $A$      | The amplitude of a function can be found by taking $\|A\|$. The sign flips it over the x axis |
| $B$      | Horizontal, or phase                                                                          |


$$ y = A * \sin(B(x-\frac{C}{B})) $$