Trigonometric Identities

I. Reciprocal Identities

 

II. Quotient Identities

 

III. Pythagorean Identities

 

IV. Cofunction Identities

 

V. Even/Odd Identities

 

VI. Sum and Difference Identities

 

VII. Double Angle Identities

 

VIII. Half Angle Identities

 

IX. Product-to-Sum Identities

 

X. Sum-to-Product Identities

 

 


XI. Other Trig Formulas

Law of Sines
       
Law of Cosines
       
Area of Triangle