Homework Statement
Question: Show that the solutions of the wave equation for a square drum head of side L can be written as:
u(x,y,t)=\sum_{k_x , k_y} A_{k_x , k_y} e^{-ik_x x - ik_y y}e^{i\omega t}
where:
\omega = a \sqrt{{k_x}^2 + {k_y}^2}
Where a is the wave-velocity and...