I'll write it over here. So we know that cosine of two theta is equal to cosine squared of theta minus sine squared of theta, which is equal to one minus two sine squared of theta, which is equal to two cosine squared theta minus one. And you can go from this one to this one to this one just using the Pythagorean identity, and we proved that in earlier videos in trigonometry on Khan Academy. Now, do any of these look useful? Well, all of these three are gonna be differences of squares so we can factor them in interesting ways. And remember, our goal at the end of the day is maybe cancel things out that are making us get this zero over zero. And if I could factor this into something that involves a one plus square root of two sine theta, then I'm gonna be in business.