You did not specify what stepper motor driver you are using; however, from your previous posts and the equations you used here, it sounds like you are using a DRV8825 carrier.
If that is the case, your first two equations look correct (depending on if you are accounting for the 70% in full-step mode); however, as Derrill mentioned in your previous thread, the DRV8825 carrier should be limited to 1.5A per phase without additional cooling. A VREF setting of 0.75V would set the current limit to 1.5A per phase. If you are only using full-step mode, you can increase the VREF to about 1.05V. This results in a current limit of 2.1A per phase, but since both coils are always on and limited to approximately 70% of the current limit setting in full-step mode, it only ever reaches about 1.5A per phase.
By the way, to correct your 3rd equation, you would need to move the 0.7 to the VREF side of the equation (VREF × 0.7 = I × 5 × Rsense). Then it simplifies down to your second equation.