Entity Relationship Diagram Symbols

This engineering drawing shows different types of geometry of butt welds.
"Welds can be geometrically prepared in many different ways. The five basic types of weld joints are the butt joint, lap joint, corner joint, edge joint, and T-joint (a variant of this last is the cruciform joint). Other variations exist as well - for example, double-V preparation joints are characterized by the two pieces of material each tapering to a single center point at one-half their height. Single-U and double-U preparation joints are also fairly common - instead of having straight edges like the single-V and double-V preparation joints, they are curved, forming the shape of a U. Lap joints are also commonly more than two pieces thick - depending on the process used and the thickness of the material, many pieces can be welded together in a lap joint geometry." [Welding. Wikipedia]
This engineering drawing example was redesigned using the ConceptDraw PRO diagramming and vector drawing software from the Wikimedia Commons file: Butt Weld Geometry.GIF.
[commons.wikimedia.org/ wiki/ File:Butt_ Weld_ Geometry.GIF]
The engineering drawing example "Butt weld geometry" is included in the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.

"In geometry a polygon is traditionally a plane figure that is bounded by a finite chain of straight line segments closing in a loop to form a closed chain or circuit. These segments are called its edges or sides, and the points where two edges meet are the polygon's vertices (singular: vertex) or corners. The interior of the polygon is sometimes called its body. An n-gon is a polygon with n sides. A polygon is a 2-dimensional example of the more general polytope in any number of dimensions. ...
The basic geometrical notion has been adapted in various ways to suit particular purposes. Mathematicians are often concerned only with the bounding closed polygonal chain and with simple polygons which do not self-intersect, and they often define a polygon accordingly. A polygonal boundary may be allowed to intersect itself, creating star polygons. Geometrically two edges meeting at a corner are required to form an angle that is not straight (180°); otherwise, the line segments may be considered parts of a single edge; however mathematically, such corners may sometimes be allowed. These and other generalizations of polygons are described below." [Polygon. Wikipedia]
The geometry diagram example "Polygon types" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mathematics solution from the Science and Education area of ConceptDraw Solution Park.