# Domain and Range of a Function

## Discrete and continuous functions and dependent and independent values

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Practice Domain and Range of a Function

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Good Tidings

Credit: Yinghai
Source: http://www.flickr.com/photos/41821150@N02/7572983836

Why do beaches have high tides and low tides? Why are tides important? When can they be deadly? Are tides the same everywhere on Earth?

#### A Range of Values

Tides are mostly a result of the moon's gravity. The moon pulls on the seas as it moves around the Earth. Its gravitational field is strong enough to move the ocean. When the moon is directly over a beach, or over the point on Earth exactly opposite the beach, the beach experiences high tide. When the moon is at a right angle to the beach, low tide occurs. Each beach experiences two high tides and two low tides per day. The tidal range, or the difference between the maximum and minimum tides, varies from place to place. The largest tidal range on Earth occurs in the Bay of Fundy, in Canada. There, the difference between high and low tides can reach over 50 feet at certain times of the year. In the Mediterranean and Caribbean Seas, on the other hand, the tidal range is close to zero.

Credit: John Lloyd
Source: http://www.flickr.com/photos/32109282@N00/2622155259/

A sizable tidal range can result in the creation of special habitats for plants and animals. Low tide can reveal tide pools, such as the one pictured above, which can be home to a variety of marine organisms, including seaweed, snails, sea anemones, crabs, and starfish. The tidal range can also be a crucial factor during hurricanes. If a hurricane comes ashore at high tide, it can cause much more damage than if it had hit at low tide.

See for yourself: http://oceantoday.noaa.gov/hurricanestormsurge/

#### Explore More

Watch the videos below to learn more about tide pools and the Bay of Fundy's extreme tides.

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