At time t$0,$ a localized magnetic field is detected at $4\mathrm{.}38,2\mathrm{.}3,0$m$,$ with a direction B$^=0\mathrm{.}6211,0\mathrm{.}7837,0.$ A short time later, this localized magnetic field is detected at $5\mathrm{.}21,5\mathrm{.}3,0$m$.$ It is determined that this magnetic field is due to passing electromagnetic radiation.

A$.$ What is k$^,$ the direction of propagation of the radiation?