1. Vocabulary 2.2 – Curves and two dimensional figures (part 1) MA418 Spring 2010 McAllister

2. Curve A set of points in a plane that can be traced without lifting the pencil A simple curve when traced never crosses a point more than once A closed curve when traced comes back to its starting place

3. Examples Simple curvesNot simple curves

4. Examples Closed curvesNot closed

5. Simple closed curves divide the plane into 3 distinct regions inside outside boundary points

6. Convex and concave figures Convex means that when any two points inside the figure are joined by a line segment, the entire line segment is inside the figure. Concave (or non- convex) means that there are pairs of points inside the figure, which when joined by a line segment, part of the segment is outside the figure.

7. Polygonal curve A curve consisting of line segments joined endpoint to endpoint.

8. Polygon A simple, closed polygonal curve

9. Parts of a polygon Sides – the individual line segments that make up the polygon Vertices – the endpoints where two line segments are joined.