00:01
Okay, so i'm going to look at the left -hand side of this equation and try to rewrite it as the right -hand side.
00:06
So looking at the left -hand side, i can rewrite sine of s minus t as the signs of traction formula, sine of s times cosine of t minus cosine of s times sine of t.
00:19
And this is all divided by sine, so i know i'm going to divide by sign to each of these terms separately.
00:29
Plus cosine of s minus t, i can rewrite that as cosine of s times cosine of t, plus sine of s times sine of t.
00:41
And i know that i'm going to be dividing by cosine of t.
00:46
So actually what i'm going to do is, well, i'm going to divide by cosine of t to each of these terms separately.
00:56
All right.
00:57
So in my first term, sign of t, there's nothing i could really simplify here, so i'm going to leave it.
01:03
Sign of t here, though, i can cancel.
01:11
Cosen of s.
01:13
I can cancel cosine of t, and then this i'm going to leave here.
01:16
Now, i have negative cosine of s plus i'm adding these two, cosine of us, and then these are going to cancel.
01:24
Okay, sweet.
01:25
So my middle two terms ended up canceling...