00:01
One thing to consider in this problem is the double angle formula for cosine of 2x, and sign of x is fine.
00:10
Now, the tricky thing then is there are three different formulas for cosine of 2x.
00:16
So i always tell my students to pick the one that deals with the other trig function in the problem.
00:21
Well, the other trig function is sign.
00:23
So just rewrite, you know, if you're looking at your formula sheet or if you haven't memorized, it's 1 minus 2 sine squared of x, and everything else is still the same.
00:38
I think the way i would do this problem is just a me thing is i would add 2 sine squared to the right side, add sine of x to the right side, and subtract 1 to the right side.
00:51
Because now you can factor this...