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Math 126

Syllabus

Highlights

Math Study Center

Questions?

You have seen

  • Derivatives...
  • Integrals...
  • Differential equations...
  • In one variable only
  • (with a smidgen of parametric motion).

We have really only equipped you to understand life on a string.

That sucks

How can we understand a situation closer to reality?

How can we

Questions we might ask:

Question

How does it feel to fly along this spiral trefoil path?

Question

How do we find lines perpendicular to a surface (even a weird one)?

Question

What makes this shape...

Question

...different from this one?

Properties we might examine

We could try to characterize shapes and objects using things like

What is reality?

Three dimensional space

  • What is it?
  • Here's a picture:
  • No, really, that's a picture. Is it missing something?

What is reality?

How can we describe this space so that we can calculate things? Get a handle on it? Use it for something?

René Descartes

Descartes thought of something brilliant, something that shook the world.

René Descartes

Descartes discovered coordinates

  • The 3D space of human experience is the set of ordered triples of numbers:
  • $$\mathbf{R^3}=\{(x,y,z) | x,y,z\in\mathbf{R}\}$$
  • Here's a picture you probably recognize.

Numbers breed numbers

We can now calculate distance!

Distance between two points $(a,b,c)$ and $(a',b',c')$ is

$$\sqrt{(a'-a)^2+(b'-b)^2+(c'-c)^2}.$$

This generalizes the Pythagorean theorem. The book has a good explanation of why it's true. See if you can figure it out (using the Pythagorean theorem) before you read it! If you have already read it, try before reading it again. (You read each section of the book several times, right?)

Numbers breed equations

We can now describe shapes!

Next time: vectors!

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