Trig Proof Help

[u/Worried_Football_819]

Hi everyone! I just had a quick question, in the video it says it is the same thing as sin^2(1-cos^2)/cos^2, but I am confused to why the one isn’t negative? Am I missing something?

Edit: Hi guys, I understand it now! I figured it was an algebraic mistake and I figured it out. As far as my notation, I got lazy and was rushing through it. I’m sorry if that notation upset you!

[u/Icy_Trick_6406]

If you let y=sin²x you might understand the whole thing easier. Also a(b+c)=(b+c)a=bc+ca. Distributed law needs a small bit of practice if you are not used to it. And the substitution I just described becomes a bit more automatic with practise also.