The solution is readily found: u ( r ) = A sin ⁡ ( k r + δ s ) {\displaystyle u(r)=A\sin(kr+\delta _{s})} .
وحل تلك المسألة : u ( r ) = A sin ⁡ ( k r + δ s ) {\displaystyle u(r)=A\sin(kr+\delta _{s})} .