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Math Help - Multiplying Trigonometric Expressions

  1. #1
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    Multiplying Trigonometric Expressions

    (cot(x)-tan(x))(cot^2(x)+1+tan^2(x))

    The answer is cot^3(x) - tan^3(x)

    I cannot get to the same outcome.

    Any help would be great thanks!
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  2. #2
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    Re: Multiplying Trigonometric Expressions

    Well, then, what do you get? You see where "cot^3(x)" and "tan^3(x)" come from, don't you. So I guess your question would be "where did all the other terms go?" There are, in fact, four other terms: cot(x) times 1 and times tan^2(x) and -tan(x) times cot^2(x) and times 1. What do those give?

    You know that "cot(x)tan(x)= 1", don't you?
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  3. #3
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    Re: Multiplying Trigonometric Expressions

    have u done this identity in school(algebra): a^3-b^3=(a-b)(a^2+b^2+a*b)???Let a=cot (x) and b=tan(x) will give a*b=1.Still without identity if you merely solve R.H.S. you can get the desired L.H.S.
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  4. #4
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    Re: Multiplying Trigonometric Expressions

    Thanks for the help! I think I got it
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