Comparison of the angular diameters for δ Cephei as a function of pulsation phases from two methods. These two methods are the interferometric technique (Mérand et al. 2005, their Table 3) and IRSB technique using the prescription given in S11, with VK band photometric light curve data taken from Moffett & Barnes (1984) and Barnes et al. (1997). Epoch of 2443674.144 days and period of 5.366316 days are adopted from Moffett & Barnes (1985). Error bars are omitted for clarity. The dashed curves are modeled angular diameters as a function of pulsational phases based on the solution of Eq. (2), using D = 273.2 pc, see text for more details.