Trigonometric Functions 

| |

1.Definition: Cosine of a Real Variable 

2.Definition: Sine of a Real Variable 

3.Definition: Tangent of a Real Variable 

4.Proposition: Continuity of Cosine and Sine 

5.Proposition: Pythagorean Identity 

6.Proposition: Additivity Theorems of Cosine and Sine 

7.Proposition: Infinite Series for Cosine and Sine 

8.Proposition: Special Values for Real Sine, Real Cosine and Complex Exponential Function 

9.Proposition: Inverse Cosine of a Real Variable 

10.Proposition: Inverse Sine of a Real Variable 

11.Proposition: Inverse Tangent of a Real Variable