Definition
Region
A region is a chosen part of a flat surface or of space, often marked by a boundary.
Continue from this idea into connected AXIO math.
What it means
When a line or curve divides a surface, each part you can point to is a region. The region is the part itself, not only the line around it. Some regions are closed in; others continue without end.
Remember it
The boundary is the fence; the region is the patch it marks.
Example
Draw one diagonal across a square. The diagonal separates the inside of the square into two triangular regions.
Watch for
Area is a number that measures how much surface a region covers; the region is the part being measured.
Common mix-up
The outline is a boundary, not the whole region. A region refers to the part selected by or around that boundary.
Exact meaning
A region is a specified part of a plane or of space; it may be bounded by curves or surfaces, or it may continue without bound.