RIDGE

Beach Problem



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A shipwreck survivor manages to swim to a desert island. As it happens the island closely approximates the shape of an equilateral triangle. She soon discovers that the surfing is outstanding on all three of the island's coasts. She crafts a surfboard from a fallen tree and surfs every day. Where should she build her house so that the sum of the distances from her house to all three beaches is as small as possible? (She visits each beach with equal frequency.) Before you proceed further, locate a point in the triangle at the spot where you think she should build her house.

de Villiers 1999 p. 23 

Drei-Strände-Problem

Einer Schiffbrüchigen gelingt es, sich auf eine verlassene Insel zu retten. Diese Insel hat, wie der Zufall es will, die Form eines gleichseitigen Dreiecks. Sie entdeckt schnell, dass es an allen drei Stränden der Insel (den Seiten des Dreiecks) wunderbare Möglichkeiten gibt zu surfen. Die Schiffbrüchige baut sich aus einem Baum ein Surfbrett und surft jeden Tag.

4 a ) Wo sollte sie ihr Haus bauen, so dass die Entfernung von ihrem Haus zu jedem der drei Strände gleich ist.

4 b) Wo sollte sie ihr Haus bauen, so dass die Summe der Entfernungen von ihrem Haus zu allen drei Stränden minimal ist? (Sie surft an allen drei Stränden gleich häufig.)

Bevor Sie genauere Überlegungen anstellen, zeichnen Sie den Punkt ein, von dem Sie denken, dass es der günstigste Ort für das geplante Haus der Schiffbrüchigen ist. Suchen Sie dann nach einer überlegten Lösung. Begründen Sie jeweils Ihre Lösung!

[Three-beach problem: A shipwrecked person manages to swim to a deserted island. This island has, as it happens, the shape of an equilateral triangle. She soon discovers that there are marvelous possibilities at all three beaches of the island (the sides of the triangle) for surfing. The shipwrecked person builds herself a surfboard from a tree and surfs every day.

4 A) Where should she build her house, so that the distance from her house is to every one the three beaches is equal?

4 b) Where should she build her house, so that the total of the distances from her house to all three beaches is minimal? (She surfs at all three beaches equally frequently.)

Before you use more exact methods, draw in the point which you think is the best place for the shipwrecked person's house. Then look for an exact solution. Justify your solution in each case!]

Knipping 2005



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Supported by a research grant from the Social Sciences and Humanities Research Council of Canada

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