Answer
Two positive coterminal angles:
$0^\circ+360^\circ=360^\circ$
$0^\circ+2\times360^\circ=720^\circ$
Two negative coterminal angles:
$0^\circ-360^\circ=-360^\circ$
$0^\circ-2\times360^\circ=-720^\circ$
Work Step by Step
In order to find the coterminal angles of a quadrantal angle, we have to add or subtract $360^\circ$.
Two positive coterminal angles:
$0^\circ+360^\circ=360^\circ$
$0^\circ+2\times360^\circ=720^\circ$
Two negative coterminal angles:
$0^\circ-360^\circ=-360^\circ$
$0^\circ-2\times360^\circ=-720^\circ$
