The displacement of particle executing periodic motion is given as :

$y= 4 cos^2(t/2)sin(1000t)$

The above expression may be considered to be result of superposition of :

- 2 waves
- 3 waves
- 4 waves
- 5 waves

I tried this by changing $cos$ function,

as $ 4 [(1+cost)/2 ] sin1000t$

but now after I think its superposition of 2 waves but given answer is 3 waves , then how should Interpret the number waves ?