Can you give examples of situations that might be modeled with trigonometric functions? That is, can you give examples of phenomena that take on a series of values over and over again?
There several situations in real life that can be modeled with trigonometric functions. Perhaps one of the most famous examples is a vibrating string, as the ones we can see in music instruments. Also, the behavior of the electric current is modeled using trigonometric functions, in particular in a circuit with alternate current. Another example is the movement of a pendulum with short oscillations
