>> Now what about situations where we're thinking about--now this time notice we're dealing with cosine. But pi over 6, we're thinking in terms of radians here and we should easily be able to flow from one to the next. Now pi over 6, pi over 6, oh that's 30 degrees. So we have to comeback over here and relabel once again. And all of this is just reference. You don't have to make the triangles anatomically correct, sort of, but relabeling is pretty important to get it right. And I don't suggest that you try to rely on memorization or anything like that. You really want to draw the diagram and if you do draw it sort of anatomically correct, that's kind of helpful but it's not necessary. Alright at any rate, we're talking about an angle here our angle theta you see is pi over 6, so this is pi over 6. Pi over 6, that's 30 degrees. So this other angle must be you see the 60-degree of business. Well, gee, just knowing this one though we can label our triangle as kinda look a little strange because pi over 6 is a really small angle, you see, and well, I'm drawing it as much as bigger angle. But at any rate, it's the idea that the short side is opposite small angle. This is the small angle, this is 1, and this is 2 and this is the square root of 3. And now for sine and cosine, it's pretty easy, you see, because we have the coordinates as the square root of 3, 1. And now sine and cosine are easy to identify. We want cosine of pi over 6, cosine remember is X over R. The X component is the square root of 3 over 2, square root of 3 over 2. Interesting that this is really 30 degrees that's 60 degrees, these then are compliments of one another. The sine and cosine, gee, sine and cosine of compliments, gee, they tend to be equal to one another. Well, there's a good reason for that and we may have a chance to take a look at it at another time. Cosine of pi over 3. Well once again, we have to go through a relabeling situation. We had it labeled like this before when we had 60 degrees right there. But let's use the radian measure idea. You see we go through all of this business of this is pi over 3, pi over 3 is 60 degrees. So this is pi over 6 or 30 degrees. And well you think about the 30 degrees because it's really easy to label that way, opposite that 30-degree angle is the one side, and then the hypotenuse is 2, and the other side is the square root of 3. Now the coordinates of the point will be 1 the square root of 3 and away we go. Cosine of this angle then is X over R or X over R, you see, it's 1/2, so 1/2.