How is Phase Shift of an Op-Amp calculated using Polar Coordinates
Your question suggests that you have unfortunately not learned complex arithmetic sufficiently well during your precalculus course. Consequently, you may struggle at the level at which you are now studying.

Nevertheless, this might help: the Argand diagram.

If you wish to know how the last figure you mention is calculated, then sqrt(102+10002) = 1000.05 and arctan(1000/10) = +89.43 degrees. To understand, or partly understand, the reason for the calculation, review the linked figure and recall your high-school trigonometry.