00:01
In this problem we have sine of alpha minus theta.
00:05
Is that equal to negative cosine of alpha? well let's look at a right triangle and examine it.
00:10
Alright, so here's a right triangle.
00:11
We have our right angle here and let's call this angle right here alpha.
00:15
And if we did that, that would make this 90, oops, 90 minus alpha.
00:23
Okay? okay, so here, if we were to take from the point of view of alpha, and we wanted to find out what sine of alpha was, we would maybe call this side a and call this side c.
00:33
Then alpha, sine of alpha, right, sine of alpha would equal a over c.
00:40
And that's an a, not a nine, that's an a.
00:43
Alright, so now let's look at cosine of, let's look at cosine of 90 minus alpha.
00:51
Alright, so if we had cosine of 90 minus alpha, then that would be also a over c, right? because from the point of view of 90 minus alpha we would have adjacent over hypotenuse.
01:03
That would also be a over c.
01:05
Equals a over c...