Word  Definition  Examples  

P  
Parabola  The curved shape you get when you graph a quadratic function  
Parallel lines  Lines that are always the same distance apart, they never cross.  Lines that have the same slope  y = 3x + 1 and y = 3x  5 are parallel because they both have slope = 3  
Parallelogram  A quadrilateral where the opposite sides are parallel  Rectangles, squares, and diamonds are parallelograms  
Pascal's Triangle  A pattern for finding the coefficients of the terms in a binomial expansion. It is also used in probability. 
1 

Percent %  A portion of 100  .65 = 65/100 = 65%  
Perfect squares  Numbers whose square roots are rational numbers  1, 4, 9, 16, 25, 36, and 49 are perfect squares ¼ is also a perfect square 

Period of a function  The horizontal length of one cycle of a periodic function. Most trigonometric functions have a period that is related to 2p radians or 360°  See Trigonometry  
Perpendicular bisector  A line, segment, or ray that is perpendicular to the original segment at its midpoint  
Perpendicular lines  Lines that cross at right angles. The product of the slopes is 1.  y = 2x + 1 and y = ½x  5 are perpendicular because 2 • (½) = 1  
Pi Π π  Most frequently used Greek letter, it represents the ratio of diameter to circumference in math problems about circles. It also represents an angle measure in radians equal to 180°  
Plane  A flat surface that extends forever in all directions. Planes have no thickness. Usually drawn as a shaded parallelogram.  
Point  A location in space that has no size. Any point can be uniquely identified by a set of coordinates (x, y).  
Point of intersection  The point where two lines intersect or cross. If the lines are represented on a coordinate grid, the coordinates for the point of intersection can be read from the graph.  
Polygon  A closed plane figure with at least three sides  A triangle is a 3sided polygon  
Polynomial  A statement with one or more terms  poly means many  5x^{2}, 72, and 3x^{2 }+ 2x  1 are polynomials  
Position vector  A vector with its initial point at the origin  
Positive angle  An angle formed by counter clockwise rotation about its endpoint.  
Postulate  An accepted statement of fact that can be used to prove theorems  "Two points define exactly one straight line" is a postulate  
Power  The exponent  x^{5} is x to the fifth power  
Probability  The chance that something will happen. For example, the probability that you will get a head when you flip one coin is 1 chance out of 2 or 1/2.  
Properties  In geometry, statements that are accepted as true and are used with deductive reasoning to prove other statements.  
Properties of equality  For all real numbers, a, b, and c: Addition: If a = b, then a + c = b + c Subtraction: If a = b, then a  c = b  c Multiplication: If a = b, then a • c = b • c Division: If a = b, and c ≠ 0, then a/c = b/c 

Proportion  A statement that two ratios are equal  two fractions that are equal 


Protractor  A device used to measure the size of an angle in degrees.  
Pure imaginary number  A complex number a + bi, where a = 0 and b is not zero  
Pythagorean theorem  In a right triangle, the sum of the squares of the lengths of the two sides (legs a and b) is equal to the square of the length of the hypotenuse (c). Click here to see an animated graphical "proof" of the theorem. 
a^{2} + b^{2 }= c^{2} 

Word  Definition  Examples  
Q  
Quadrants  The coordinate xy plane is divided into four quadrants by the x axis and y axis. Quad means four. The quadrants are usually labeled with roman numerals, starting at the top right and numbering counterclockwise. 


Quadratic equation  An equation written in the form ax^{2} + bx^{ }+ c = 0
where a, b, and c are real numbers and a ≠ 
The largest exponent is 2  2x^{2}  3x^{ }+ 4 = 0  
Quadratic formula 


Quadratic function  A function with an equation written in the form y = ax^{2} + bx^{ }+ c where a ≠ 
Graph as a parabola  the largest exponent is 2  y = 2x^{2}  3x^{ }+ 4  
Quadrilateral  A geometric figure with four sides and four angles  A rectangle is quadrilateral  
Word  Definition  Examples  
R  
Radian  A unit of measure for angles, used in trigonometry, calculus, and advanced math and physics. 
π radians = 180° 

Radical  A square root sign or any other root, like a cube root or fourth root 
√5 

Radius  In a circle, any segment that has one endpoint at the center of the circle and the other endpoint on the circle  
Range  The set of all possible output values of a function  the dependant variable. For functions in x and y, the possible y values are the range.  Possible answers  for y = x the range is all positive numbers and 0  
Ratio  Comparing two numbers by division  A fraction  ¾ and 3:4  
Rational expression  An expression with fractions, especially when there is a variable in the denominator. The variable can not make the denominator equal to zero  
Rational number  A number that can be written as a fraction. This includes whole numbers, fractions, and decimals that truncate (end) or repeat.  ½, ¾, 2.5 and 3 are rational  
Rationalize the denominator  Make the denominator of a fraction a rational number without changing the value of the expression  Get rid of any √ 


Ray  The part of a line consisting of one endpoint and all the points extending forever in one direction  
Real number  A number that is either rational or irrational  All numbers except imaginary numbers  √5, ½, ¾, 2.5, 0, π and 3 are real numbers  
Reciprocal  Multiplicative inverse of a nonzero number. The product of a number and its reciprocal is 1.  To get the reciprocal;
Flip it! 


Rectangle  A parallelogram with four right angles  
Regular polygon  A polygon that is both equilateral and equiangular.  
Relation  Any set of ordered pairs  
Relationship symbols  Symbols that compare two numbers. This includes the equal sign. 
5 < 7 

Remote interior angles  For each exterior angle of a triangle, the two nonadjacent angles  
Repeating decimal  A decimal expression of a fraction, where the digits repeat. The repeating part is written with a bar over it to represent that the pattern repeats infinitely.  1/3 = 0.33333...  
Resultant  The answer in vector addition  
Rhombus  A parallelogram with four congruent sides  A diamond is a rhombus  
Right Angle  An angle that measures 90° 
x = 90° 

Right Triangle  A triangle that has one 90° angle. The other two angles will add up to 90°  
Rise  The vertical change between two points on a graph. The slope of a line is the rise divided by the run.  
Run  The horizontal change between two points on a graph. The slope of a line is the rise divided by the run. 
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