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.
: This scientist studies living organisms and l iving systems. Botanist. : This scientist studies plants. Chief scientist. : This scientist leads other scientists in a particular research area. Ecologist. : This scientist studies the relationship of living things with their living and nonliving. environment. Economist. : This scientist studies economics. Economics is a social science that addresses the production, distribution, and use of goods and services.