Lesson 5: Answers/hints for exercises

  1. Compare an Earth globe with a Mercator projection (A Mercator projection is identified by its straight latitude lines and longitude lines.) In particular, compare the sizes of Canada. If the maps are of different scale, then make your comparison by comparing Canada with Brazil in each case. Estimate the ratio of Canada's apparent area on the Mercator projection with that on the globe.
    On a mercator or similar projection, the area of Canada appears to about twice that of Brazil. On a spherical model of Earth, the areas of Canada and Brazil appear as approximately equal. Relative to countries near the Equator, and whose areas therefore change very little under mercator projection, the area of Canada appears to approximately double under mercator projection.
  2. Repeat exercise (1) for Ecuador.
    Because of Ecuador's location on the Equator, its area is distorted very little under mercator projection.
  3. Compare the ratios obtained in Exercises (1) and (2). Decide whether they are approximately equal or obviously different. Explain your conclusion.
    They are obviously different. Distortion of shape and area under mercator projection increases with distance from the equator.
  4. Describe three projections other than the Mercator projection and the primary advantage(s) of each.
    see Classification of map projections.

 

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Materials developed by-
Wm. Rundberg
College of San Mateo
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