00:01
All right, and your question, it implies we're trying to verify this identity.
00:06
So verifying identities, we usually pick which side looks more complicated to work on first because it's easier to work on a side here, say on the left side and simplify it.
00:20
It's easier to do that than it is to unsimplify this side and try to make it match the left side.
00:27
So typically we try to say which side looks more complicated, and work on that.
00:34
So looking at this left side, i see that i should be able to use the cosine difference identity.
00:41
And the cosine difference identity says that if i subtract two angles like we have shown here, that is equal to cosine of the first angle times cosine of the second angle plus sign of the first angle, sign of the second angle.
00:58
And that is all over our current denominator of sine of alpha, cosine of b.
01:04
Now, this denominator is the common denominator.
01:10
So i'm going to split this apart into two separate fractions being added...