00:01
Okay, so we're looking for two angles that give us a positive cosine.
00:11
We know cosine is going to be positive in the first quadrant here.
00:17
So, cosine is positive here.
00:21
This is the first quadrant.
00:24
So cosine is positive here.
00:26
And it's also positive in the fourth quadrant.
00:29
So cosine is positive here also.
00:30
So we're looking for two thetas, one in here.
00:37
First quadrant and the other one here.
00:45
So the first one we'll find it by finding the inverse of this.
00:51
Theta is going to be cosine inverse of this value here...