Definition: Angles in the
standard position
where the
terminal
side lies on the x or y axis. For example: 90°, 180° etc.
Try this:
Adjust the angle below by dragging point A and see which angles are quadrantal.
A quadrantal angle is one that is in the
standard position
and has a measure that is a multiple
of 90° (or π/2 radians). A quadrantal angle will have its
terminal
lying along an x or y axis.
In the figure above, drag the point A around and see which angles are quandrantal angles.