Quadrilateral. In Euclidean plane geometry, a quadrilateral is a polygon with four sides (or 'edges') and four vertices or corners. Sometimes, the term quadrangle is used, by analogy with triangle, and sometimes tetragon for consistency with pentagon (5-sided), hexagon (6-sided) and so on.
Some environmental scientists and specialists focus on environmental regulations that are designed to protect peopleâs health, while others focus on regulations designed to minimize societyâs impact on the ecosystem.
Definition of environmental studies?   Environmental Studies is the interdisciplinary study of how humans interact with their environment. This field examines all aspects of the natural environment, social enâ¦vironments, politics, ecology, etc., and how they all work together.