00:01
Okay, two more trick functions to evaluate here.
00:04
We got sign of negative pi over six and then cosine of pi.
00:11
Okay, so we're actually going to do these using our unit circle.
00:15
Okay, a couple of points on our unit circle.
00:18
Draw this nice and big.
00:20
So negative pi over six.
00:22
This is the same as negative 30 degrees.
00:24
So we know negative angles take us in a clockwise direction.
00:28
So going around negative 30 degrees.
00:31
Okay.
00:31
We can put the sides on this triangle as 1, root 3, 2, using our knowledge of special triangles.
00:37
The 1 will actually be negative because of the direction it's going down.
00:41
Okay.
00:42
And then we know that sign is the opposite over the hypotenuse...