SSC SSC-Maths Trigonometry

Theory : Trigonometry

Trigonometric Identities and Formulas

There are three systems of measuring Angles-

1. Circular System

  • Unit of Measurement is radian.
  • 180 degree = π radians

2. Sexagesimal System (English System)

  • Right angle is divided into 90 equal parts called degree.
  • Unit of Measurement is degree.
  • Each degree is divided into 60 equal parts called minute. (1 degree = 60’)
  • Each minute divided into 60 equal parts called seconds (1 minute = 60’’)

3. Centesimal or French System

  • Right angle is divided into 100 equal parts.
  • Unit of measurement is grades.
  • Each grade is divided into 100 equal parts called minute, and minutes into seconds.

Sign Conventions

  • cos (90 – θ) = sinθ
  • tan (90 – θ) = cotθ
  • cosec (90 – θ) = secθ
  • sec (90 – θ) = cosecθ
  • cot (90 – θ) = tanθ

Some Basic Formulas and Identities

  1. sin2θ + cos2θ = 1
  2. 1 + tan2θ = sec2θ
  3. 1 + cot2θ = cosec2θ

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