Trigonometry Notes:Trig Functions

This material appears in section 4.2.

• Definitions of Trig Functions
  
  • Sine
    Sine () of a number θ is the -coordinate of the point on the unit circle at angle θ. This makes sine a function with domain and range .
  • Cosine
    Cosine () of a number θ is the -coordinate of the point on the unit circle at angle θ. This makes cosine a function with domain and range .
  • Tangent
    

    

    Range is all reals.

  • Cotangent
    

    

    Range is all reals.

  • Secant
    

    

    Range is

    

  • Cosecant
    

    

    Range is

    

Important Values to Memorize

θ	0
sin(θ)	0				1
cos(θ)	1				0

Notice in this table that you could think of the values of as

sin(θ)

and takes the same values but in the opposite order.