There are many functions in trigonometry. One of the most interesting trigonometry therorem i've came across is the Demoivre's therorem. Simpler ones would consist of the trigonometric functions of obtuse angles. Or u can take a look at the trigonometry table for futher reference.
Trigonometric functions vary with the size of an angle.
The six commonly used trigonometric functions can be defined in terms of an acute angle in a triangle.