**pair 一对**

Two identical, similar, or corresponding things that are matched for use together:a pair of gloves; a pair of earrings.

**palindrome 回文（指顺读和倒读都一样的词语）**

A word or phrase that reads the same backwards as forwards, for example, madam, nurses run, Madam, I’m Adam or Poor Dan is in a droop.

**palindromic numbers 回文数**

The number likes 1347431, 20058385002,

**parabola 抛物线**

A plane curve formed by the intersection of a right circular cone and a plane parallel to an element of the cone or by the locus of points equidistant from a fixed line and a fixed point not on the line. It like the path of an object thrown into the air and falling back to earth.

**parallel 平行**

Two or more straight coplanar lines, planes, or a line and a plane that do not intersect. Or designating curves or surfaces everywhere equidistant.

**parallelogram 平行四边形**

A quadrilateral having both pairs of opposite sides parallel and equal to each other.

**parameter 参数**

- A constant or variable term in a function that determines the specific form of the function but not its general nature, as a in f(x) = ax, where a determines only the slope of the line described by f(x).
- One of the independent variables in a set of parametric equations.
- Statistics: a variable entering into the mathematical form of any distribution such that the possible values of the variable correspond to different distributions.
- Computers: a variable that must be given a specific value during the execution of a program or of a procedure within a program.

**parentheses 括号**

One of a pair of shallow, curved signs, ( ), used to enclose an additional inserted word or comment and distinguish it from the sentence in which it is found.

**pattern 模式，图样**

A decorative design, as for wallpaper, china, or textile fabrics, composed of elements in a regular arrangement.

**pentagon 五边形**

A polygon with five sides and five angles.

**pentagonal number 五角数**

A pentagonal number is a figurate number that extends the concept of triangular and square numbers to the pentagon, but, unlike the first two, the patterns involved in the construction of pentagonal numbers are not rotationally symmetrical. The nth pentagonal number pn is the number of distinct dots in a pattern of dots consisting of the outlines of regular pentagons with sides up to n dots, when the pentagons are overlaid so that they share one vertex. For instance, the third one is formed from outlines comprising 1, 5 and 10 dots, but the 1, and 3 of the 5, coincide with 3 of the 10 – leaving 12 distinct dots, 10 in the form of a pentagon, and 2 inside. 1, 5, 12, 22, 35, 51, 70, 92, 117, 145, 176, 210, 247, 287, 330 …

**pentagram 五角星形**

A five-pointed, star-shaped figure made by extending the sides of a regular pentagon until they meet, used as an occult symbol by the Pythagoreans and later philosophers, by magicians, etc.

**pentahedron 五面体**

A solid figure having five faces.

**pentomino 五格拼板**

A polyomino of order 5, that is, a polygon in the plane made of 5 equal-sized squares connected edge-to-edge. When rotations and reflections are not considered to be distinct shapes, there are 12 different free pentominoes. When reflections are considered distinct, there are 18 one-sided pentominoes.

**percent 百分之…, 百分率**

- One part in a hundred, 1/100.
- Figured or expressed on the basis of a rate or proportion per hundred (used in combination with a number in expressing rates of interest, proportions, etc.): %.

**perfect square 完全平方**

An integer that is the square of an integer. Such as 4 is perfect square of 2, 100 is perfect square of 10.

**perimeter 边界；周长**

- The border or outer boundary of a two-dimensional figure.
- The length of such a boundary.

**permutation 排列**

The act of changing the order of elements arranged in a particular order, as abc into acb, bac, etc., or of arranging a number of elements in groups made up of equal numbers of the elements in different orders, as 123, 132, 213, 231, 312, 321; a one-to-one transformation of a set with a finite number of elements.

**perpendicular 垂直**

- Being at right angles to the horizontal; vertical.
- Intersecting at or forming right angles.

**perpendicular lines 垂线**

A line or plane perpendicular to a given line or plane.

**perspective 透视**

A system for the representation of three-dimensional objects on a plane or other surface while taking into account the objects’ spatial structure and the distances of the objects’ various parts from the observer. It represents people and things that are far away as being smaller than those that are nearer the front

**pi 圆周率**

The ratio of the circumference of a circle to its diameter. The symbol for pi is π.

π = 3.141592653589793238462643…

**pie chart / pie graph 饼图**

A graphic representation of quantitative information by means of a circle divided into sectors, in which the relative sizes of the areas (or central angles) of the sectors correspond to the relative sizes or proportions of the quantities.

**pint 品脱（容量单位，为D加仑，在英国等国家约合 0.568 升，在美国约合 0.473 升）**

A unit for measuring liquids and some dry goods. There are 8 pints in a gallon, equal to 0.568 of a litre in the UK and some other countries, and 0.473 of a litre in the US.

**place value 位值**

The value of the place, or position, of a digit in a number or series: In the number 794, the location of the digit 4 has a place value of one.

**plane 平面；飞机**

- Flat surface of infinite extent but no thickness. A plane is determined, or defined, by any of the following: (1) three points not in a straight line; (2) a straight line and a point not on the line; (3) two intersecting lines; or (4) two parallel lines.
- A flying vehicle with wings and one or more engines.

**Platonic Solids 柏拉图立体**

Any of the five possible regular polyhedra: cube, tetrahedron, octahedron, icosahedron, and dodecahedron. Also called (esp formerly): Platonic body.

**plot 制图**

- A plan, map, diagram, or other graphic representation, as of land, a building, etc.
- To locate (points or other figures) on a graph by means of coordinates, or to draw (a curve) connecting points on a graph.

**plus 加; 加号**

- Increased by the addition of: Two plus two is four.
- The plus sign: +.

**PM 下午**

Afternoon.

**point 点**

- A dimensionless geometric object having no properties except location.
- An element in a geometrically described set.

**point symmetry 点对称**

A group composed of all rigid motions or similarity transformations of some geometric object onto itself.

**polar coordinates 极坐标**

A pair of coordinates for locating a point in a plane by means of the length of a radius vector, r, which pivots about the origin to establish the angle, θ, that the position of the point makes with a fixed line. Usually written (r, θ).

**polygon 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.

**polyhedron 多面体**

A three-dimensional geometric figure formed of many faces.

**polynomial 多项式**

An algebraic expression consisting of one or more summed terms, each term consisting of a constant multiplier and one or more variables raised to nonnegative integral powers. For example, x^{2} – 5x + 6 and 2p^{3}q + y are polynomials. Also called multinomial.

**population 人口**

The total number of persons inhabiting a country, city, or any district or area.

**position 位置**

The place where something is located.

**positive 正**

**power 乘方，幂**

**power set 幂集**

The collection of all subsets of a given set.

**prime factor 素因数**

The prime factors of a quantity are all of the prime quantities that will exactly divide the given quantity.

**prime number 素数**

A positive integer that is greater than 1 and can be divided exactly only by itself and 1, for example 7, 17 and 41.

**principal 首要的；本金**

- First or highest in rank, importance, value, etc.; chief.
- Capital or property, as contrasted with the income derived from it.

**prism 棱柱体; 棱镜**

- A solid figure whose bases or ends have the same size and shape and are parallel to one another, and each of whose sides is a parallelogram.
- A transparent glass or plastic object, often with ends in the shape of a triangle, which separates light that passes through it into the colours of the rainbow.

**probability 可能; 几率, 或然率**

A number, ranging from zero to one, expressing either the projected likelihood that a specific event will occur or the observed ratio of the number of actual occurrences to the number of possible occurrences.

**problem 问题**

A question that can be answered by using logical thought or mathematics.

**product 乘积**

The number or quantity obtained by multiplying two or more numbers together.

**profit 利润**

Financial gain from a transaction or from a period of investment or business activity, usually calculated as income in excess of costs or as the final value of an asset in excess of its initial value.

**pronumeral 变项，未知数**

A symbol representing such a quantity. For example, in the expression a^{2} + b^{2} = c^{2}, a,b, and c are variables.

**proper fraction 真分数**

A fraction in which the numerator has a lower absolute value than the denominator.

**proportional 按比例；比例项**

- (Of a first quantity with respect to a second quantity) a constant multiple of: The quantity y is proportional to x if y = kx, where k is the constant of proportionality.
- (Of two quantities) having the same or a constant ratio or relation: in a/b = c/x, x is the fourth proportional.

**protractor 量角器**

An instrument for measuring or drawing angles on paper, usually a flat semicircular transparent plastic sheet graduated in degrees.

**pyramid 锥体; 金字塔**

- A solid figure with a polygonal base and triangular faces that meet at a common point.
- (In ancient Egypt and pre-Columbian Central America) A quadrilateral masonry mass, stepped and sharply sloping, used as a tomb or a platform for a temple.

**Pythagoras Theorem 毕达哥拉斯定理**

The sum of the squares of the lengths of the sides of a right triangle is equal to the square of the length of the hypotenuse.