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  1. J

    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...
  2. J

    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)...