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Solves real-world problems involving decimals.

When a Ruler Is Too Short

Surveyors are often seen in the middle of the street making careful measurements of angles with their transits, and distances with their steel tapes. For points than can be easily reached, such a survey is convenient. But when the target is inaccessible – a mountain summit or a distant star – known distances can be combined with measured angles to determine a distance or altitude. The method relies on parallax, the way an object appears to move, relative to a more distant background, when viewed from different angles.

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Volcanoes and Urban Planning

The numerous annual volcanic eruptions that occur worldwide evidence the potential dangers they often create. Volcanoes are found across a wide variety of geologic settings, including subduction zones (i.e.: Andes, Cascades, Aleutian Islands) and hotspot settings (i.e.: Hawaii-Emperor Seamounts, Galapagos, Azores). Regardless of their location, history has demonstrated that volcanoes pose a vivid and real hazard to regional settlements and environments. The eruption of Mt. St. Helens (Washington - 1980), Nevado del Ruiz (Colombia - 1985), Mt. Hudson (Chile - 1991), Mt.

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