# Search results

1. ### Division by zero

Why doesn't someone just define it!!! ;)
2. ### Are these equal?

I'm obviously not writing the formula out correctly since the answer is not the same. I was just solving how I'v written it out [(2cos^2 - 1)(2cos^2-1)] + [(2cos^2-1)(2cos^2-1)] Is there another way to write out cos(4x) as cos(2x+2x) instead of cos 2[(cos2x)^2-1] and have the answer come out...
3. ### Are these equal?

I'm verify some trigonometry equations and am confused about a couple of things. (This is self-study, I'm not in school) The equation cos4x = 1+8cos^4-8cos^2 can be solved by re-writing as 2(cos2x)^2 -1 and factoring out which yields the correct answer, however based on what i've seen in...
4. ### I can't figure this Trig Identity out help please?

Thanks, uart, I finally figured it out. I was starting on the left side instead of the right. After factoring and factoring and factoring it finally worked out! I've never factored so much in my life!!! Joe
5. ### I can't figure this Trig Identity out help please?

I need to verify the given identity. I've tried every which way i can think of, but can't figure this one out. I am self-studying this book "College Trigonometry 5th Edition by Aufmann. This is exercise set 3.3, problem 63. cos^2(x) - 2sin^2(x)cos^2(x) - sin^2(x) + 2sin^4(x) = cos^2(2x)...