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Parallax method


While exploring some rocky cliffs, you notice a lighthouse in the distance that you can't quite reach. It would be nice to know how far away that lighthouse is, but there is no way to make a direct measurement over the uneven terrain. Luckily you have your trusty compass and some knowledge about parallax and triangles!
For the first vantage point, you start with the lighthouse directly north of you. You then pace out 120 steps (about 100 meters) west. From this new spot, you measure the angle between due north and the lighthouse as 12 degrees.
Given that, determine the average distance to the lighthouse. (Round to 1 decimal place.)
  • Your answer should be
  • an integer, like 6
  • an exact decimal, like 0.75
  • a proper fraction, like 1/2 or 6/10
  • an improper fraction, like 10/7 or 14/8
  • a mixed number, like 1 3/4