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Introduction to Trigonometric Functions definitions

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  • Degree
    A unit for measuring angles, where a full circle is divided into 360 equal parts.
  • Radian
    A unit for measuring angles based on the arc length equal to the radius of a circle; a full circle is 2π of these.
  • Circumference
    The total distance around a circle, calculated as 2π times the radius.
  • Reference Angle
    An acute angle formed by the terminal side of a given angle and the nearest x-axis.
  • Quadrant
    One of four regions in the coordinate plane, determined by the x and y axes.
  • Sine
    A trigonometric ratio comparing the length of the side opposite an angle to the hypotenuse in a right triangle.
  • Cosine
    A trigonometric ratio comparing the length of the adjacent side to the hypotenuse in a right triangle.
  • Tangent
    A trigonometric ratio comparing the length of the side opposite an angle to the adjacent side in a right triangle.
  • Hypotenuse
    The longest side of a right triangle, always opposite the right angle.
  • SOHCAHTOA
    A mnemonic device summarizing the definitions of sine, cosine, and tangent using side ratios in right triangles.
  • Conversion Factor
    A multiplier, such as π/180 or 180/π, used to switch between degrees and radians.
  • Unit Circle
    A circle with radius one, centered at the origin, used to define trigonometric values for all angles.
  • Sign Convention
    A rule indicating which trigonometric functions are positive in each quadrant of the coordinate plane.
  • All Students Take Calculus
    A mnemonic for remembering which trigonometric functions are positive in each quadrant.