00:01
So in this problem, we're being asked to prove the given identity.
00:03
Well, let's first take a look at our first expression.
00:06
We have sine squared theta minus one.
00:08
Well, this looks like one of our pythagorean identities.
00:11
Well, one of our pythagorean identities says that sine square the theta plus the cosine square the theta is equal to one.
00:19
So if i were to isolate the cosine square the theta, that would be cosine square the theta is equal to one minus the sine square the theta.
00:26
Well, notice that this is the opposite signs.
00:28
So if i multiply both sides of this equation by negative 1, that would be negative the cosine square the theta equal to negative 1 plus the sine square the theta.
00:37
Well, sine square theta minus 1 is the same thing.
00:40
So now we can substitute a negative cosine squared in place of that first preemphasy...