Describe the difference between Geographic Coordinate Systems and Projected Coordinate Systems.

A projected coordinate system is defined on a flat two-dimensional surface. Unlike a geographic coordinate system, a projected coordinate system has constant lengths, angles and areas in both dimensions.

Explanation:

Locations on earth are often expressed in geographic degrees (latitude and longitude). But when you are doing a topographic survey you need to speak in meters and feet. This is because, depending on the application, it uses a geographic or projected coordinate system.

A geographic coordinate system (GCS) is a coordinate system that uses a three-dimensional spherical surface (ellipsoid) to define locations on the earth. A common choice of coordinates is latitude and longitude.

In a projected coordinate system (PCS), you project the geographic coordinate that you have measured, for example, in a cylinder that easily unfolds over a two-dimensional surface (the map).