Answer
90$^{\circ}$ is between 1st and 2nd quadrant.
Work Step by Step
1. This is "if applicable" situation your book is talking about
2. 90$^{\circ}$+360$^{\circ}$=450$^{\circ}$
90$^{\circ}$-360$^{\circ}$=-270$^{\circ}$
Co-terminal angles always in the same quadrant as original angle.
