00:01
Okay, so we're starting with cotangent, which is a cosine over sign.
00:05
So instead of rewriting co -tangent, i'm just going to write what it equals.
00:09
And then we have a plus this one minus two cosine squared over, oh, is it, sine times cosine? so as i explain this to students, i often ask them, like, what's missing in this fraction that this fraction has? students understand what i'm talking about and i'm sorry if that doesn't make it sense to you but i want the denominators to be the same so the only way i can multiply the denominator by cosines if i also multiply the numerator by cosine because technically i multiply by one and multiply by one does not change the value so now the denominators are the same and i can put them together and in the numerator i have cosine squared plus one minus two cosine squared.
01:11
So i didn't do anything with the right fraction, but i can put them together.
01:14
Let's change colors again.
01:16
So what do i have in the numerator? i have one cosine square minus two cosine square.
01:23
That's a negative one cosine square.
01:26
And let's review something for a second.
01:31
Sin theta, cosine theta.
01:32
I haven't changed that at all...