00:01
Okay, so for this problem, we're asked to evaluate sine, sorry, sign of 150 degrees using reference angles.
00:12
So, 150 degrees, if we graph it on a coordinate plane, if we have zero here, we have 90 degrees there, 180 degrees there, and 270 degrees here, 150 degrees would be somewhere in the second quadrant.
00:31
So this would be the angle 150 degrees.
00:36
And the reference angle we're looking for is this angle right here.
00:41
So if it's in the second quadrant to find the reference angle, it's simple.
00:47
It's 180 degrees minus the angle, so it's minus 150 degrees.
00:53
And we get 30 degrees.
00:58
So the new problem we're solving is sign of 30 degrees.
01:02
Now, let me draw a 30 -60 -90 special triangle to help us solve this.
01:07
So we have 60 degrees here.
01:10
This is a 90 degree angle.
01:12
And we have 30 degrees there...