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A centimeter (symbol: cm) is a unit of length in the International System of Units (SI), the current form of the metric system. It is defined as 1/100 meters. History/Origin A centimeter is based on the SI unit meter, and as the prefix 'centi' indicates, is equal to one hundredth of a meter. Metric prefixes range from factors of 10-18 to 1018 based on a decimal system, with the base (in this case the meter) having no prefix and having a factor of 1. Current Use The centimeter, like the meter, is used in all sorts of applications worldwide (in countries that have undergone metrication) in instances where a smaller denomination of the meter is required. Height is commonly measured in centimeters outside of countries like the United States. Feet Definition A foot (symbol: ft) is a unit of length in the imperial and US customary systems, equal to 12 inches or exactly 0.3048 meters. History/Origin The foot has ancient origins, originally based on the length of a human foot. It was standardized over time, with the current definition established in 1959 with the international yard and pound agreement. Current Use The foot is widely used in the United States and to a lesser extent in the UK for measuring height, distance, and in construction. It remains the standard unit for aviation altitude measurements worldwide. (责任编辑：) |