Advertisement

Online Math Dictionary: P

Easy to understand math definitions for K-Algebra mathematics
Just scroll down or click on the word you want and I'll scroll down for you!
 

parabola parallel parallelogram
Pascal's triangle pentagon pentagram
percent perimeter permutations
perpendicular pi piecewise function
point polygon polyhedron
polynomial positive numbers prime
prism probability product
proof proper fraction proportion
pyramid Pythagorean Identities Pythagorean Theorem
Pythagorean triples    

 

Parabola
The formula for the standard parabola is
                                
f(x)=x^2
For more info and examples, check out myParabola lesson.
For graphing parabolas, check out my Graphing Parabolas lessons (first in a series).

parabola

red line

Parallel
Two lines (lying in the same plane) are parallel if they never intersect...  This means that the two lines are always the same distance apart.

parallel lines

red line
Parallelogram
parallelogram is a quadrilateral (a four sidedpolygon) where both pairs of opposite sides are parallel.
For more info, check out Properties of Parallelograms.

parallelogram

 

Pascal's Triangle
Pascal's triangle was created by a French mathematician named Blaise Pascal.  To build the triangle,  start with the three 1's  at the top and put 1's down the sides.  To get the numbers in the middle, you add the two numbers right above.   To get the  4, you add 1+3.   To get the 10, you add 4+6.

Pascal's Triangle

So, what's the next line?     6   15   20   15   6   1
And it just keeps going!
For more advanced info, check out my Binomial Theorem lesson and my Binomial Theorem Revisited lesson.

red line

Pentagon
A pentagon is a five sided 
polygon.   The pentagon in the picture on the right is a regular pentagon because all the  sides and angles are the same (congruent).

For more info on hexagons, check out my properties of pentagons page.

pentagon

red line

Pentagram
pentagram is made by connecting the vertices of a pentagon with straight lines.  Then, thepentagon is erased.   You can also make hexagrams from hexagons, octagrams fromoctagons and so on.

For a related brain bender, check out The Handshake Puzzle.

pentagram

red line

Percent
Percents are like fractions and decimals because they count PART of something.   Whole numbers (0, 1, 2, 3, ...) count whole things  -- like a whole pizza.   You can use a percentages to count part of the pizza.  Half of a pizza would be 50% of a pizza.  One-fourth of a pizza would be 25% of a pizza.

Examples:   20%      0.05%       245.2%

red line

Perimeter
Pretend that the shape on the right is a big park...  The perimeter is the amount offencing you'd need to close it all in.

For more info on perimeters,  check out my reference page on perimeter formulas.

perimeter

red line

Permutations
A permutation is an arrangement of objects.
Example:  How many ways can you arrange the letters AB and C?  6 ways
       ABC     ACB     BAC     BCA     CAB     CBA
For more info, check out my Permutations lesson.

red line

Perpendicular
Two lines are perpendicular if they intersect in a 90 degree (right) angle.

perpendicular

red line

Pi
In a circlepi is the ratio of the circumference to the diameter.
                                  
pi = circumference/diameter

                                         pi =  3.1415926...
Pi is an irrational number (which means that its decimal part goes on forever and never repeats.)

circle

red line

Piecewise Function
A piecewise function is a function that is defined (and graphed) in two or more pieces.
For more info,  check out my lesson on Graphing Piecewise Functions.
piecewise defined function

red line

Point
A point is a location in space.  I can't even draw you a real picture of a point, because my dot would really be a blob of points.  It's impossible to really draw just one point.  So, when you're in Algebra and you have to graph points, you'll just have to pretend.

red line

Polygon
A polygon is a geometric shape made up of vertices that are connected with line segments.

For more specific info, check out one of my "Properties of" pages on triangles,quadrilateralspentagonshexagonsheptagonsoctagonsnonagonsdecagons11-gonsor dodecagons.

polygon

red line

Polyhedron
A polyhedron is a three-dimensional object whose faces are polygons.  The most famous set of polyhedra (that's the plural) is the five Platonic Solids that may have been discovered by Pythagoras.  These solids are special because they are the only ones that are made up of regular polygons.   They are the tetrahedron, the cube (hexahedron), the octahedron, the dodecahedron and the icosahedron.
For more info, check out my Polyhedra Gallery.   

polyhedron - icosahedron

red line

Polynomial
For now (and probably forever), you can just think of a polynomial as a bunch of blobs that are being added and subtracted.  The blobs are just products of numbers and variables (letters) with exponents.  Here's an example:
                                                      polynomial:  f(x)=2x^3+7x^2-x+5
For more info and more examples, check out my Polynomial lessons.

red line

Positive Numbers
Positive numbers are those that appear to the right of zero on the number line.
                               number line with positive numbers

red line

Prime
A number is prime if it has exactly two factors:  1 and itself.  The number 20 is not a prime number since it has more than two factors:  1, 2, 4, 5, 10, 20.  The number 20 is composite.  The number 1 is neither prime nor composite since it only has one factor: 1.
Here are some prime numbers:  2, 3, 5, 7, 11, 13, 17, 19, 23, 29, ...

red line

Prism
A prism is a polyhedron that is formed with two parallel polygons (the bases - top and bottom)that are connected at the edges with rectangles.  My example in the picture is a right prism since the sides form right (90 degree) angles with the bases.

prism

red line

Probability
A probability tells us how likely it is for an event to occur.  When the weatherman says there's a 60% chance of rain, that's a probability.  When you toss a coin, there's a 50% (1/2) probability that "tails" will come up.  
Let's look at rolling a die...  There are 6 possible rolls (1, 2, 3, 4, 5, 6).  This number goes in the denominator.  What if we want to know the probability for rolling a 5...  There is one 5 on a die...  So, there's one chance out of six that we'll roll a 5.  That's a 1/6 probability.  What if we want to roll an odd number?  There are three odd numbers on a die (1, 3, 5)...  That's three chances out of six...  That's a 3/6 (or 1/2) probability.

red line

Product
The product is the answer when you multiply two (or more) numbers.
Example:   3 x 2 = 6  
For more info, check out my Multiplication Lessons.

red line

Proof
A proof is an argument that shows something (like a theorem) is true beyond any doubt.  In math, sometimes a proof is all numbers and symbols  and sometimes there are sentences too.
There are different kinds of formal proofs in math:  direct proof, indirect proof and mathematical induction, to name a few.

red line

Proper Fraction
Proper fractions really aren't any more correct than improper fractions, but elementary school teachers like you to use them.  A proper fraction is when the numerator is less than the denominator.
For more info on fractions, check out my lessons on fractions.

proper fraction

red line

Proportion
A proportion is simply two ratios that are equivalent to each other.  Proportions are usually used in Algebra to solve for some missing information.

proportion:  2/3 = x/9

red line

Protractor
A protractor is a device used in Geometry to measure and draw angles.

red line

Pyramid
A pyramid is formed when triangles are put on a polygon base (a square in my picture).  These triangles meet at a single vertex above the base.

pyramid

red line

Pythagorean Identities
The Pythagorean Identities are
   
For more info on the Pythagorean Identities and where they come from, check out my Pythagorean Identities lesson.

red line

Pythagorean Theorem
This is kind of creepy in words, but an easy equation.  Here are the words:  The sum of the squares of the lengths of the legs of a right triangle is equal to the square of the length of the hypotenuse.

                                     Pythagorean Theorem:  a^2+b^2=c^2

Pythagorean Theorem

red line

Pythagorean Triples
Pythagorean triples are also called Pythagorean numbers.  These are whole numbers that work together in the Pythagorean theorem.

3^2 + 4^2 = 5^2                    5^2 + 12^2 = 13^2

 

A B C D E F G H I no 
J's
K L M
N O P Q R S T U V W no 
X's
no 
Y's
no 
Z's