<Li> North - south compression equals the cosine of the latitude (the reciprocal of east - west stretching): equal - area cylindrical . This projection has many named specializations differing only in the scaling constant, such as the Gall--Peters or Gall orthographic (undistorted at the 45 ° parallels), Behrmann (undistorted at the 30 ° parallels), and Lambert cylindrical equal - area (undistorted at the equator). Since this projection scales north - south distances by the reciprocal of east - west stretching, it preserves area at the expense of shapes . </Li> <P> In the first case (Mercator), the east - west scale always equals the north - south scale . In the second case (central cylindrical), the north - south scale exceeds the east - west scale everywhere away from the equator . Each remaining case has a pair of secant lines--a pair of identical latitudes of opposite sign (or else the equator) at which the east - west scale matches the north - south - scale . </P> <P> Normal cylindrical projections map the whole Earth as a finite rectangle, except in the first two cases, where the rectangle stretches infinitely tall while retaining constant width . </P> <P> Pseudocylindrical projections represent the central meridian as a straight line segment . Other meridians are longer than the central meridian and bow outward, away from the central meridian . Pseudocylindrical projections map parallels as straight lines . Along parallels, each point from the surface is mapped at a distance from the central meridian that is proportional to its difference in longitude from the central meridian . Therefore, meridians are equally spaced along a given parallel . On a pseudocylindrical map, any point further from the equator than some other point has a higher latitude than the other point, preserving north - south relationships . This trait is useful when illustrating phenomena that depend on latitude, such as climate . Examples of pseudocylindrical projections include: </P>

Which group of map projection is suitable for mapping equatorial region