  We analyze the possibility of experimental investigation of new low-energy
relations between the values of resonance masses in the meson form factors and
the differential rate of radiative kaon decay $K^+\to \pi^+ e^+e^-(\mu^+\mu^-
)$ at the current level of the experimental precision. A set of arguments is
listed in favour of that these relations can be a consequence of weak static
interactions in the Standard Model.
