Sine and Cosine

This is for my homies in maths class. I know many of you fear the sin & cos.

cosine is walking east-west, sine is walking north-south

They’re just a way to convert from circular coordinates to square coordinates.

polar coordinates "at sea" versus rectangular coordinates "in the city"

You want to get to the red dot. If you’re at sea you set your bearing θ and sail straight there. If you’re in the city you walk north and then east.

Cosine tells you how far you have to walk crosstown; sine is how far uptown.

 

That’s basically it. If you think uptown and crosstown look like legs of a right triangle, you’re thinking along the right track to understand where the many sin & cos formulæ come from.

Here’s a GPL’ed picture of why we think of cosine as a wave:

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