Can someone help explain this trigonometry equation to me with a detailed development?
sin^{2}a - cos^{2}a = 1-2 x cos^{2}a
thank you!
One of the most basic identities to memorize because you will use it frequently is: . Rearrange this to get the by itself, and then substitute for the term in your equation - what do you get? By the way, you could also have replaced the term in your equation to get a different form of the same equation, all of which are equal to .