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Math Help - please help

  1. #1
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    please help

    determine the reference angle 0' for the given angle 0=195 or 120
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  2. #2
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    Quote Originally Posted by melissa
    determine the reference angle 0' for the given angle 0=195 or 120
    The reference angle is always the angle between the line made by the given angle, theta, and either the +x or -x axis depending on which gives you the smaller angle. In fact, a reference angle is always an acute angle or a right angle. Also, a reference angle is always considered to be positive.

    So. 195 degrees is in the third quadrant, just under the -x axis. The reference angle is thus 195 - 180 = 15 degrees.

    120 degrees is in the second quadrant. So the reference angle is 180 - 120 = 60 degrees.

    Two last examples:
    42 degrees. If an angle is in the first quadrant, the angle is its own reference angle, so the reference angle here is 42 degrees. (If you like, the angle is above the +x axis, so 42 - 0 = 42 degrees.)

    315 degrees. This is a fourth quadrant angle, so it is below the +x axis. Thus 360 - 315 = 45 degrees is the reference angle.

    -Dan
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  3. #3
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    Mellisa please place your thread in appropriate section, i.e. trigonomtery. I h8 moving threads around!
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