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Homework Help: Refrence Angles & Positive/Negative Angles(Coterminals) HOW?

  1. Jun 2, 2004 #1
    my question is, how do you "Find one positive angle and one negative angle that are coterminal with each angle." :

    For example:

    [tex]\frac{5\pi}{12} [/tex]

    And also, I had a question on this as well:

    Find the reference angle for each angle with the given measure.
    [tex]\frac{12\pi}{5} [/tex]

    i noe that you have to see what quadrant it is in, then from there, you use the Reference Angle Rule, whichever one. But what if the measure is a negative number? Like for example, [tex]-210\circ[/tex]?? What would you do here?

    if anyone can help me with these i'd be really gratefull! thanks!!
  2. jcsd
  3. Jun 3, 2004 #2


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    Given some angle, x, you can find a positive angle co-terminal with x by adding [itex]2\pi[/itex] to x until you get a positive number, and you can figure out how to find a negative angle.
    To find the reference angle for any angle, keep continuing to add or subtract [itex]2\pi[/itex] until you get a value, x, such that [itex]0 \leq x < 2\pi[/itex]. Of course, you'll have to figure out whether you need to add, subtract, or neither.
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