There is a large variety of types of problems which rely heavily on
trigonometric functions. Many problems fall into this category because of
their cyclical nature. Clearly, due to the cyclical nature of the graphs of
the trig functions 
and 
, we see that they can be very helpful here.
Other problems deal with right triangles in a strong fashion. Due to the
definitions of the trigonometric functions in terms of such triangles,
we see that they are natural tools to use in solving such problems.
In an attempt to highlight some of these applications, we will mention several below and briefly point out how the trig functions can be used to solve them.