Fig. 22.

Sector, a portion of a cicle comprehended between any two radii and their intercepted arcs. - Similar Sectors are those whose radii include equal angles.

To find the area of a sector. Say as 360° is to the degree, etc., in the arc of the sector, so is the area of the whole circle to the area of the sector. Or multiply the radius by the length of the arc, and half the product will be the area.