In an equidistant projection, which property is true?

In an equidistant projection, which property is true?

• A. Distances are true only from the center of projection or along a special set of lines
• B. Areas are preserved for continents only
• C. Angles are preserved at most locations
• D. Directions are true along all parallels

Answer: (A)

Distances from the projection center to any location on the map are true in an equidistant (azimuthal equidistant) projection. This means the scale is accurate along every ray starting at the center, so reading the radius gives the real Earth distance from the center to that point. Distances between two points that aren’t along the same radial line aren’t kept true, which is why only the distances from the center (or along those radial lines) are preserved. Areas, angles, and most directions aren’t maintained in this type of projection, so the other statements don’t hold as general truths.