an area or portion that is distinct from others.
The belt of southern sectors from Sectors 31 to 49 and Sectors 20, 21, 22 and 23 were affected.
the plane figure enclosed by two radii of a circle or ellipse and the arc between them.
For example, Figure 4a shows three such rings formed from the sectors and rectangle in Figure 3a.
a mathematical instrument consisting of two arms hinged at one end and marked with sines, tangents, etc., for making diagrams.
He also learned on his own how to use a compass, sector , and other instruments to make astronomical predictions, including that of eclipses.