Two guitar strings, 1 and 2 , plucked simultaneously produce standing waves described by

\[\begin{aligned}
& D_{1}=A \sin (a x) \cos (b t) \\
& D_{2}=A \sin (q x) \cos (d t),
\end{aligned}\]

with \(a=14.5 \mathrm{~m}^{-1}, b=2512 \mathrm{~s}^{-1}, q=19.3 \mathrm{~m}^{-1}\), and \(d=2575 \mathrm{~s}^{-1}\).

(a) What is the frequency of each wave? 

(b) What is the beat frequency of the combined wave?