Trigonometry, abbreviated as TRIG, is a branch of mathematics that deals with the relations between the sides and angles of plane or spherical triangles.

Trigonometry Terms

  • Arccos - The inverse cosine.
  • Arccot - The inverse cotangent.
  • Arccsc - The inverse cosecant.
  • Arcsec - The inverse secant.
  • Arcsin - The inverse sine.
  • Arctan - The inverse tangent.
  • Cosecant - The ratio of the hypotenuse over opposite side in a right triangle.
  • Cosine or cos - The ratio of the adjacent side of the hypotenuse in a right triangle.
  • Cotangent - The ratio of the adjacent side to the oposite in a right triangle.
  • Hero's formula -
  • Heron's formula -
  • Hyporenuse - The side of right triangle opposite the right angle, which is the longest side.
  • Infinite - Having no boundary.
  • Law of cosines - An equation relating to cosine of an interior angle and the lengths of the sides of a triangle.
  • Law of sines - The ratio of the sine of any angle within any specific triangle and the length for the opposite side is a constant.
  • Orthocenter - The point of concurrence of the altitudes of the triangle.
  • Orthogonal - Perpendicular to a plane.
  • Pythagorean theorem - An equation relating the lengths of the sides of a right triangle.  The sum of the squares of the legs of a right triangle is equal to the square of the hypotenuse.
  • Proportional - In a constant ratio.
  • Ratio - A constant proportion or two real numbers divided by each other.
  • Sine or sin - The ratio of the length of the opposite side to the length of the hypotenuse.
  • Tangent or tan - The ratio of the opposite side to the adjacent side of a right triangle.
  • Tangent line - A line that touches the graph of the function at a single point.
  • X-axis - The horizontal axis on a coordinate system.
  • Y-axis - The vertical axis on a coordinate system.
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Law of Cosines
Law of Sines
Trig Function Abbreviations
Trig Function Equations
Trig Functions