I'm taking a precalculus class in college and our text is seriously lacking in explanation. There is this one topic which I don't understand and every time someone tries to explain it, I get don't fully grasp the logic. The concept of theta naught. Is this everything that isn't theta? Here is a word problem from the text:

Here is an example of one of the problems:

Sven is running clockwise around a circular track. Sven runs at 3.5 meters per second,

and it takes him 82 seconds to complete a lap of the track. From his starting point, it takes

him 14 seconds to reach the southernmost point of the track.

After running for 20 minutes, how far (in a straight line) is Sven from the northmost point

of the track?

So, my problem again is theta naught. I understand how to find angular speed and how to find the radius. I know the formula for finding their coordinates but within that formula we are to take X=rCos(wt+(theta naught)). I've been told that its always calculated from the positive x axis but what I don't get is literally what exactly I'm trying to get. I think if I can understand what it literally is, this will make sense to me. Is it everything but the theta?