# Table Of Trigonometric Identities

Table of Trigonometric Identities
Definitions
Angle Sum and Difference Formulas
 
a
sin
sin cos
cos sin
sin
c
 
cos
cos cos
sin sin
b
cos
tan
tan
 
c
tan
1 tan tan
a
tan
b
Double Angle Formulas
 
sin 2
2sin cos
Basic Identities
 
1
1
2
2
cos 2
cos
sin
sin
cos
csc
sec
2
2 cos
1
1
1
tan
cot
 
2
1 2sin
cot
tan
2 tan
 
1
1
tan 2
csc
sec
2
1 tan
sin
cos
Half Angle Formulas
Periodicity
 
1 cos 2
sin
2
sin
2
sin
2
cos
2
cos
 
1 cos 2
2
cos
 
 
tan
tan
2
 
1 cos 2
2
tan
 
Pythagorean Identities
1 cos 2
2
2
sin
cos
1
2
2
sec
tan
1
Sum-to-Product Formulas
2
2
csc
cot
1
 
 
sin
sin
2sin
cos
2
2
Quotient Identities
 
 
sin
cos
sin
sin
2cos
sin
tan
cot
2
2
cos
sin
 
 
cos
cos
2cos
cos
Co-Function Identities
2
2
 
 
sin
cos
cos
sin
 
cos
cos
2sin
sin
2
2
2
2
tan
cot
cot
tan
2
2
Product-to-Sum Formulas
1
 
 
sin sin
cos
cos
csc
sec
sec
csc
2
2
2
1
 
 
cos cos
cos
cos
2
Even or Odd Symmetry
 
 
 
1
sin
sin
cos
cos
 
 
sin cos
sin
sin
 
 
2
 
 
tan
tan
cot
cot
1
 
 
 
 
cos sin
sin
sin
 
csc
csc
sec
sec
2