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## 以 i 开头的数学词汇

2012-10-07
i   虚数单位

icosahedron   二十面体
A regular polygon bounded by 20 equilateral triangle faces, with 12 vertices and 20 edges.

identity   恒等式；同一性
An equation which states that two expressions are equal for all values of any variables that occur. Such as

x2 – y2 = (x + y)(x – y)

imaginary number   虚数
A number of the form a + bi, where i = √-1, a and b are real numbers and b ≠ 0.

Imperial System   英制
Conforming to standards or definitions legally established in Britain: relating to a system of measurement in which weight is measured in pounds, length is measured in feet, and volume is measured in pints.

improper fraction   假分数
An arithmetic fraction whose numerator is greater than or equal to the denominator—for example, 5/3, 4/4.

incenter   内心
The center of the circle inscribed in a triangle, that point where the bisectors of the angles of a triangle or of a regular polygon intersect.

inch   英寸
A unit of length in the US Customary and British Imperial systems, equal to 1/12 of a foot (2.54 centimeters).

incircle of triangle   三角形的内切圆
A circle inscribed within a triangle.

included angle   夹角
The angle between the free-stream vector and the longitudinal axis of a body.

increase   增多，提高
To become greater or larger in amount, number, value, etc.

independent event   独立事件
Two events are statistically independent if the probability of their occurring jointly equals the product of their respective probabilities. Also known as stochastic independence.

index   指数；索引

• A number or symbol, often written as a subscript or superscript to a mathematical expression, that indicates an operation to be performed, an ordering relation, or a use of the associated expression. In the equation 42 = 16, the number 2 is an index.
• Computers: a value that identifies and is used to locate a particular element within a data array or table.

inequality   不等式
A mathematical statement indicating that two quantities are not equal, represented by the symbol <, >, or ≠, meaning less than, greater than, and not equal to.

infinite   无限的
Not finite, without any finite or measurable limits

infinity   无限
The limit that a function ƒ is said to approach at x = a when ƒ(x) is larger than any preassigned number for all x sufficiently near a.

inflation   通货膨胀
A persistent increase in the level of consumer prices or a persistent decline in the purchasing power of money.

The radius of the inscribed circle of a triangle.

inscribe   内切
To draw (a geometric construction such as a circle, polygon, etc) inside another construction so that the two are in contact but do not intersect.

integer   整数
A member of the set of positive whole numbers {1, 2, 3, … }, negative whole numbers {-1, -2, -3, … }, and zero {0}.

interest   利息

• A charge for the use of credit or borrowed money.
• A charge expressed as a percentage per time unit of the sum borrowed or used, usually one year.

interest rate   利率

interior angle   内角

• Any of the four angles formed between two straight lines intersected by a third straight line.
• An angle of a polygon contained between two adjacent sides.

intersect   相交
To have one or more points in common.

intersection   相交; 交集

• The point or locus of points where one line, surface, or solid crosses another.
• A set that contains elements shared by two or more given sets. Also called meet, product. Symbol: ∩

interval   间隔; 区间

• A period of time between two events.
• A space between objects, points, or units, especially when making uniform amounts of separation
• A set of numbers consisting of all the numbers between a pair of given numbers along with either, both, or none of the endpoints.

inverse   逆；对立面；对立面

• Operating on a specified member of a set to produce the identity of the set: the additive inverse element of x is –x, the multiplicative inverse element of x is 1/x.
• Containing two variables such that an increase in one results in a decrease in the other: the volume of a gas is in inverse ratio to its pressure.

inverse proportional function   反比例函数
A function of the form: y = k/x, The graph is called a hyperbola.

inverse operation   逆运算
The function that replaces another function when the dependent and independent variables of the first function are interchanged for an appropriate set of values of the dependent variable: f and g are inverse functions if f(x)=y and g(y)=x.

irrational number   无理数
A real number that cannot be expressed as a ratio between two integers.

irregular polygon   不规则多边形
A closed plane figure bounded by three or more straight sides that meet in pairs in the same number of vertices, and do not intersect other than at these vertices. The sum of the interior angles is (n–2) × 180° for n sides; the sum of the exterior angles is 360°. A regular polygon has all its sides and angles equal. Specific polygons are named according to the number of sides, such as triangle, pentagon, etc.

isosceles triangle   等腰三角形
A triangle with two equal sides.

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