00:05
All right.
00:06
We need to prove this identity is true.
00:09
And we need to show that the left side and the right side are the same.
00:14
And noticing on the left, oops, noticing on the left here, we have cosine theta plus sine theta minus sine cube theta over sine theta.
00:23
On the right, i've got cotangine of theta plus cosine square theta.
00:27
I think this might be one of those problems where it might be easiest to try to get everything written in terms of sine and cosine.
00:33
So i'm going to start working on the right.
00:37
And what i'm going to do, i'm going to replace co -tangent with what i know cotangent is equal to, which is cosine of theta over the sine of theta plus the cosine squared of theta.
00:57
Now, what i'm going to need to do is get a common denominator.
01:03
So i will need to multiply cosine squared theta, right? this is really cosine squared data over one.
01:11
So if i multiply by sine theta over sine theta, then i will get the fraction, cosine squared theta times sine theta over sine theta.
01:25
So this will, when i combine the two fractions, we will get cosine of theta plus sine theta times the cosine squared data all over sine of theta...