a set of points such that for every pair of points there is a nonnegative real number called their distance that is symmetric and satisfies the triangle inequality.是什么意思_a set of points such that for every pair of points there is a nonnegative real number called their distance that is symmetric and satisfies the triangle inequality.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句