[NOISE] >> Welcome,

in this unit we’ll be learning about Trigonometry.

Trigonometry is the study of angles of triangles.

Let’s look at the technical definition.

Trigonometry is a branch of mathematics that deals with relationships between

sides and angles of triangles, and the calculations based on them,

particularly involving trigonometric functions.

You can think of trigonometry as kind of having four components.

We want to study both triangles, circles, and

the relationships between the angles of these objects.

We look at three main trigonometric functions, sine, cosine and tangent,

and we want to study oscillatory behavior.

As we see in this graph here, the functions that oscillate back and forth.

Let's look at a simple example.

When you're a kid, you might have had a slinky toy.

Well, the slinky toy is a great example of oscillatory behavior.

Notice if I take my Slinky and bounce it.

I get some oscillations.

The Slinky oscillates back and forth.

You can also take the Slinky and make some waves.

When I make waves with my Slinky, that's another example of oscillatory behavior.

Notice that the polynomials we've been studying so

far, won't be able to account for this type of behavior.

Polynomials can have some wiggles to them, but

eventually they either tend to infinity or minus infinity.

So we need some sort of function with periodic behavior.

By periodic I mean, it oscillates with time and does the same thing over and

over again, forever and ever.