Extended Trubnikov emissivity is evaluated to oblique propagation to the magnetic field in the spherically symmetric relativistic Maxwellian case. Using the extended Trubnikov expression, electron cyclotron emission (ECE) spectra and electron temperature profiles are calculated in a reactor-grade tokamak. We investigate the possibility of electron temperature profile Te(r) measurement from second-harmonic extraordinary (X)-mode ECE by changing the propagation direction. The observation angles all are scanned in solid angle to find out when the relativistic effects of the third-harmonic ECE on second- harmonic ECE decrease are minimal. The measurable Te from second-harmonic X-mode becomes high by increasing the angle between the propagation sight line and the equatorial plane because of the avoidance of the overlap region between the second and third harmonics, but the spatial resolution becomes worse. The antenna is not necessarily located around the equatorial plane. The second X-mode and the fundamental ordinary (O)-mode for the Te(r) measurement from ECE are best in the cases of Te(0) 24 keV and 24 keV Te(0) 50 keV, respectively. When the electron density, the magnetic field, and/or the inverse aspect ratio increase, the measurable Te decreases.