Question

Why and how the sines and cosines functions are simple periodic?

Answer 1

Dear student,

Sine and cosine functions are periodic because their values repeat after certain period of time.
if you observe the graph of sine/cosine curve, it oscillates between -1 to 1, cutting many times at x axis, so it repeats its zero value many times. Hence it is periodic.

mathetically we can find out its period. for a simple sine/cosine curve, it is 2pi.

therefore we can use sine/cosine equations to represent repetitive motions or oscillations

Regards