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  1. There are six trigonometrical ratios. Three are fundamental and other three are their reciprocals.
  2. The six trigonometrical ratios are
    • sine
    • cos
    • tan
    • cosec (reciprocal of sin)
    • sec (reciprocal of cos)
    • cot (reciprocal of tan)
  3. sine: The ratio of perpendicular to hypotenuse is called sine of an angle.
    sine α = perpendicular/hypotenuse
    sine α = p/h
  4. cos: The ratio of base to hypotenuse is called cosine of an angle.
    cos α = base/hypotenuse
    cos α = b/h
  5. tan: The ratio of perpendicular to base is called tangent of an angle.
    tan α = perpendicular/base
    tan α = p/b
  6. cosecant: The ratio of hypotenuse to perpendicular is called cosecant of an angle.
    cosec α = hypotenuse/perpendicular
    cosec α = h/p
  7. secant: The ratio of hypotenuse to base is called secant of an angle.
    sec α = hypotenuse/base
    sec α = h/b
  8. cot: The ratio of base to perpendicular is called cotangent of an angle.
    cot α = base/perpendicular
    cot α = b/p
  9. Trigonometric Tables: