$=5 \sin \frac{2 \pi}{3} x \cos 40 \pi t$
The standard equation of a stationary wave is
$y=2 a \sin k x \cos \omega t$
Comparing $(i)$ and $(ii),$ we get $\mathrm{k}=\frac{2 \pi}{3}$
or $\frac{2 \pi}{\lambda}=\frac{2 \pi}{3}$ or $\lambda=3 \mathrm{\,cm}$
Separation between two adjacent nodes is
$\frac{\lambda}{2}=\frac{3}{2}=1.5 \mathrm{\,cm}$
An observer located near these two sources of sound will hear