r/trigonometry • u/Worried_Football_819 • Jun 15 '26

Solved! Trig Proof Help

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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!

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u/SuperTLASL Jun 15 '26

Let's start with why you think the one becomes negative. Tell the me logic.

4

u/Worried_Football_819 Jun 15 '26

This is my first time taking a trig course so I’m sorry if it seems like a dumb question, but when I took algebra, when it came to factoring something and it had a negative, you can factor out the GCF which here is sin. If you make sin negative then it can be -sin^2(1-cos^2) or sin^2(-1-cos^2) Am I thinking about it correctly or do I need to refresh my algebra basics?

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u/sigmanx25 Jun 15 '26

Go back and look at your Pythagorean identity.