Contour lines do not ever cross one another because each line represents a different elevation on a topographic map. However, contour lines may merge in the case of a vertical cliff. More » Math Geometry Shapes

On topographic maps, V-shaped contour lines that point downhill indicate sharp, narrow ridge lines. Ridge lines help people recognize areas of high and low ground when hiking, fishing, hunting or engaging in other outdoo... More » Geography Maps & Cartography

A set of points that all lie within the same line are said to be collinear. According to Wolfram Mathworld, three points are collinear if and only if the distance between one point and the line formed by the other two po... More » Math Geometry
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Contour lines on a map indicate elevation or depth. Numeric notations on contour lines refer to the level of elevation, or height above sea level. More » Geography Maps & Cartography

A contour in geography refers to a line on a contour or topographical map that designates a specific and constant elevation above sea level. Contour lines are used to express a three-dimensional image of terrain on a two... More » Geography Maps & Cartography

The term "contour interval" refers to the vertical distance between contiguous contour lines in terms of elevation. Commonly illustrated on a topographic map, the elevations between contour lines are uniformly spaced alo... More » Geography Maps & Cartography

A regular heptagon has seven lines of symmetry. Each one runs from a vertex to the opposite side, bisecting the side at a 90-degree angle. More » Math Geometry Shapes