00:01
As we look at this problem where we have, i hope i'm reading it correctly just because of the location of things, cosine of x minus sign of x, that quantity is being squared and then plus sine of 2x.
00:24
And what we need to show is that that equals 1.
00:28
So starting with this left side, being squared means that you're multiplying by itself.
00:32
And so what i need to do is think about, well, if you, let's just rewrite it.
00:39
Cosign of x minus sine of x times cosine of x minus sign of x.
00:47
And while i'm at it, i'll also mention that this is a double angle formula, that that equals two sine of x, cosine of x.
00:54
Because at this point, you would distribute.
00:58
So you're looking at cosine square root of x.
01:01
The outside's a negative sine, cosine.
01:04
The inside's a negative sine, cosine...