Notices to investigation of symbiotic binaries. I. Effective temperatures of cool components

A comparison of synthetic spectra for cool giants with the observed broad-band optical/IR photometry is suggested to estimate the effective temperature, T_eff, of cool components in symbiotic binaries. The uncertainties of such estimates are within a range of 100-300 K. Here we demonstrated this approach on EG And and AX Per, and found T_eff (EG And) = 3 500 +200/-100 K and T_eff (AX Per) = 3 400 +/- 150 K. These results agree well with those obtained from empirically determined dependencies of effective temperature upon spectral type.