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Reference Angles definitions

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  • Reference Angle
    Always positive and measured to the nearest x-axis, matching a common angle in quadrant 1 for quick trig value calculation.
  • Quadrant
    One of four regions on the unit circle, each affecting the sign of trigonometric values based on angle location.
  • Unit Circle
    A circle with radius one, used to visualize angles and their corresponding trigonometric values.
  • Coterminal Angle
    Shares the same terminal side as another angle, found by adding or subtracting full circle rotations.
  • Terminal Side
    The ending position of an angle on the unit circle, used to determine coterminal angles.
  • Trigonometric Value
    Numerical result for sine, cosine, or tangent, determined by the reference angle and quadrant sign.
  • Sine
    Represents the y-coordinate on the unit circle, positive or negative depending on the quadrant.
  • Cosine
    Represents the x-coordinate on the unit circle, sign changes with quadrant location.
  • Tangent
    Ratio of y to x on the unit circle, sign determined by the quadrant and reference angle.
  • ASTC
    Mnemonic for remembering which trigonometric function is positive in each quadrant: All, Sine, Tangent, Cosine.
  • Radian
    Angle measure based on arc length, used alongside degrees for unit circle calculations.
  • Degree
    Traditional angle measure, used to locate positions and reference angles on the unit circle.
  • X-Axis
    Horizontal axis on the unit circle, used as a reference for measuring angles and finding reference angles.
  • Y-Axis
    Vertical axis on the unit circle, helps determine the sign of trigonometric values.
  • Common Angle
    Standard angles in quadrant 1, such as 30, 45, or 60 degrees, used as reference for other angles.