[en] Experimental results of nuclear magnetic resonance (NMR) in a canted antiferromagnet Fesub(1-x)Gasub(x)BO3 are reported. For an understanding of the origin of signal the influence is investigated of static magnetic fields on the parameters of NMR. It is shown that the nuclei in domains make the main contribution in a NMR signal at 77 K. The NMR method is also used for the investigation of photomagnetic effect in FeBO3. (author)