Which is NOT a common map projection?

The correct answer is Tangent because it is not a recognized or commonly used map projection in the field of cartography. The term "tangent" may relate to the concept of tangential projections, which can sometimes describe how certain projections touch the globe at specific points, but it does not refer to a standalone map projection like the others listed.

On the other hand, the Robinson projection is known for its compromise in representing various geographic features while minimizing distortion in shape, area, distance, and direction. It is often used in world maps. The Lambert projection, specifically the Lambert Conformal Conic projection, is widely used for aeronautical charts and mapping regions with a larger east-west extent. The Mercator projection, which preserves angles and is commonly used for marine navigation, is one of the most famous and widely used projections despite its size distortion at higher latitudes. Thus, while the other projections are established and frequently utilized in mapping, Tangent does not have a standing as a recognized map projection in common use.