00:01
So today we are learning about reference angles.
00:04
And the way that you can think about a reference angle is that this is the angle from your given angle to the x -axis.
00:12
So the first example that we're going to do today is 120 degrees.
00:18
It's usually helpful to draw out a sketch of where that is.
00:25
So zero is over here.
00:30
0 degrees and then up here we have 90 and here is 180 and so 120 would be 90 plus 30 degrees so right around there is going to be our 120 and so you'll notice how let me see if i can switch colors here how far from 120 to the x -axis you can measure it either in this direction with red or in this direction, which i've drawn out with blue.
01:12
But you can see that the closer one is using red.
01:17
And this angle is 180 minus 120, which is 60.
01:31
So the answer for the reference angle of 120 degrees is 60 degrees.
01:39
So next let us move on to our second example.
01:44
Our next example is going to be negative 210 degrees.
01:51
So again, let's start by drawing out our picture.
01:58
Okay, so this time we're in the negative, so we're going to be going this direction.
02:03
So again, zero is here.
02:06
We come around here, and this is negative 180...