Philippa M. Rhodes

*Island Treasure*

A young man was going through the attic of his grandfather's house and
found a paper describing the location of a buried treasure on an particular
Island. The note said that on the island one would find a gallows, an oak
tree, and a pine tree. To locate the treasure one would begin at the gallows,
walk to the pine tree, turn right 90 degrees and walk the same number of
paces away from the pine tree. A spike was to be driven at that point. Then
return to the gallows, walk to the oak tree and turn left 90 degrees and
walk the same number of paces away from the oak tree. Drive a second spike
in the ground. The midpoint of a string drawn between the two spikes would
locate the treasure.

The young man and his friends mounted an expedition to the island but
found the oak tree and the pine tree but no gallows. It had eliminated years
ago without a trace. They returned home with the map below and no treasure.

Show them where to look for the treasure.

**Try assuming an arbitrary location for the gallows and use GSP to
construct the location of the two spikes. Now move the location of the gallows.
What happens? Why?**

What happens?

The location of the treasure is the same regardless of the location of
the gallows.

Click **here **for a GSP file to move
the gallows?

**Return to Philippa's EMT 725 Page**