What is the period of #f(t)=sin( t / 14 )+ cos( (t)/21 ) #?
The period for both sin kt and cos kt is
The periods of the two separate oscillations in f(t) are
The period for the compounded oscillation is such that 28 M = 42 N, for lowest positive integers M and N. Easily, M =3 and N = 2. These give the LCM common value