Phase is introduced as a checked time shift divided by a period. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

Phase starts as a checked timing fraction

The period is 8 seconds and the lag is 1 second.

phase fraction=18\text{phase fraction} = {1\over 8}
Phase timingThe period, lag, and phase bars are checked.periodlagphasephase

The degree tag is derived from that fraction

One eighth of a cycle is 45 degrees.

18360=45{1\over 8}\cdot 360^\circ = 45^\circ
Derived phase tagThe diagram binds the timing fraction.periodlagphasephase