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← 07-37 Uncharted Territory

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Showing Revision 1 created 07/23/2012 by Amara Bot.

  1. All right. Are you with me? It's time to push forward into uncharted territory.
  2. We're going to go out of the first quadrant. When we look at our axis like this.
  3. Remember we called this the first quadrant, this the second, the third and the fourth.
  4. So far everything has been between 0 and 90° and we found that
  5. all of our trig functions have been positive.
  6. I could take the sine of an angle, the cosine of an angle, the tangent of an angle.
  7. It didn't matter--all of these trig functions are positive.
  8. Let's see what happens if we go into new quadrants.
  9. For example, let's look at this angle in the second quadrant. So now we're looking at this entire angle.
  10. Now I want to know--what is the sine of that angle or the cosine of that angle,
  11. but first let me tell you what the angle is.
  12. This angle has 3π/4 radians--now, what I do in these situations is I still make my right triangle
  13. relative to this x axis baseline--we can think of it as.
  14. Now you go to Google and type these in. I know this is sort of a menial task,
  15. but there's a good reason to type these in, get an answer and tell me what you get.