00:01
I'm going at this problem with following the directions, i guess, that you have that cosine of x minus sine of x plus 1 times the other fraction, cosine of x plus 1, all over.
00:23
Let me just write out that it's being multiplied first.
00:26
I got to get this down first.
00:28
First, cosine of x plus sine of x plus 1 minus 1 times cosine of x plus 1.
00:40
Okay, so first of all, you have the numerator correct.
00:43
So let me just put a box around that and just say, make sure you leave your numerator alone.
00:47
But let's look at the denominator a little bit closer.
00:50
If you distribute, i agree with cosine squared.
00:53
But then you have to distribute again.
00:55
Cosine times 1 is just cosine.
00:58
But now i need to distribute the sine in here.
01:00
So that's sine of x cosine of x times here that's sine of x and then minus cosine of x because negative one times anything is just that thing but negative and then negative one times one is negative one so what i'm thinking about here is these cosines of x's cancel good they're gone but then from here, i'm thinking about what is equal to cosine squared of x.
01:34
And what i'm thinking about is how sine squared plus cosine squared equals one.
01:42
So what if i subtract sine squared over, then cosine squared of x equals one minus sine squared of x...