Trigonometric Identities

Here is a list of some important trigonometric identities used. These identities are useful for students in class 10, 11 and 12. Also, candidates writing competitive exams can apply these formulae to solve trigonometric functions / equations and problems in calculus.

1.  Basic Definitions

These identities define the six basic trigonometric functions:

2.  Pythagorean Identities

3.  Reciprocal Identities

4.  Quotient Identities

5.   Co-Function Identities

6.  Even-Odd Identities

7.  Sum and Difference Identities

8.  Double Angle Identities

9.  Half Angle Identities

10.  Sum-to-Product Identities

11.     Product-to-Sum Identities

12. Law of Sines and Cosines

Law of Sines

Law of Cosines

13. Power Reducing Identities

14. Periodicity Identities

These describe the periodic nature of trigonometric functions:

15.  Inverse Trigonometric Identities

These involve inverse trigonometric functions:

16. Miscellaneous Identities