Three particles \(A, B, C\), each of mass \(m\), are connected by light inextensible strings \(AB, BC\), each of length \(a\). The particles are placed on a smooth horizontal table so that the strings are tight and the angle \(ABC\) is equal to \(90^\circ\). The particle \(B\) receives a blow of impulse \(I\) in the direction \(DB\), where \(D\) is the mid-point of \(AC\). Find the initial velocities of all the particles.