parabola: the set of all points in a plane that are equally distant from a fixed point (called

the focus) and a fixed line, (called the directrix).

paraboloid: a surface that is formed by rotating a parabola about its axis.

parallel: two lines are parallel if they are in the same plane and never intersect.

parallelepiped: a solid figure with six faces such that the planes containing two opposite

faces are parallel. Each face is a parallelogram.

parallelogram: a quadrilateral with opposite sides parallel.

pentagon: a five sided polygon.

percent: a fraction in which the denominator is assumed to be 100.

perfect number: a number that is the sum of all its factors except itself. For example, 6.

perimeter: the sum of the lengths of the sides of a polygon.

period: the measure of how often a function repeats its same values.

periodic function: a function that keeps repeating the same values.

permutation: the permutation of n things taken j at a time is:

n!
------
(n - j)!

perpendicular: two lines are perpendicular if the angle between them is 90 degees.

pi: the ratio of the circumference of a circle to its diameter.

plane: a flat surfaces that stretches off into infinity.

polar coordinates: a coordinate system of ordered pairs in which the first number of the

pair represents distance from the origin, and the second number of the

pair represents the angle of inclination from the horizontal axis.

polygon: the union of several line segments that are joined together so as to completely

enclose an area.

polyhedron: a solid that is bounded by plane polygons.

polynomial: an algebraic expression of the form:

axⁿ + bx^(n-1) + .......+ cx³ + dx² + ex + k

positive number: a real number greater than zero.

postulate: a fundamental statement that is assumed to be true without proof.

power: a number that indicates the operation of repeated multiplication.

prime number: a number whose only factors are itself and 1.

product: the result of two numbers being multiplied.

proper fraction: a fraction whose numerator is less than its denominator.

proportion: an equation of fractions in the form:

a/b = c/d

proportional: If y = kx, then y is said to be proportional to x.

protractor: a device for measuring angles.

pyramid: the union of all line segments that connect a given point and the points that lie

on a given polygon.

Pythagorean Theorem: the theorem that relates the three sides of a right triangle:

a²+ b² = c²

pythagorean triple: three natural numbers that satisfy the pythagorean theorem.