Algebra
In arithmetic, you always know
what numbers you are working with... Like
8 -
2
= 6. In algebra,
one or more of these numbers is unknown. They usually
put an "x" in for the mystery
number. Can you guess what x
is here? 7
+ x
= 15.
Easy! Of course, it gets a little harder than that...
But, it's not bad.
I've got a ton of algebra
lessons on the site! |
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Algorithm
This is what they call it when Al
Gore tries to dance. Ok, I know that was a really bad
joke, but, typing out all these definitions is making me a
bit loopy! An algorithm is a set of steps to complete
a task. It may be the list of steps it takes to find
the answer for a long division problem... Or it may be
part of a computer program... It can even be the list
of steps it takes for you to get ready to go to school in
the morning. |
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Alternate exterior angles
When a
pair of parallel lines is
intersected by a
transversal (like in the diagram on the
right), angles A
and H are a set of
alternate exterior angles and
B and G are a
set of alternate exterior angles.
In a drawing like this (where
there is a set of parallel
lines intersected by a
transversal), alternate exterior angles are
congruent (the same size.) |
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Alternate interior angles
When a
pair of parallel lines is
intersected by a
transversal (like in the diagram on the
right), angles C
and F are a set of
alternate interior angles and
D and E are a
set of alternate interior angles.
In a drawing like this (where
there is a set of parallel
lines intersected by a
transversal), alternate interior angles are
congruent (the same size.) |
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Alternating
Sequence
An alternating sequence is a list
of numbers that goes positive,
negative, positive,
negative... or negative,
positive,
negative, positive.
Example: -1,
2,
-3,
4,
-5,
6,
-7,
8, ...
For more info on sequences, check out my "What's
a sequence?" lesson. |
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Amplitude
The amplitude of a graph
or a curve is kind of the
height of the graph...
You take the height above the x-axis (4
in the pic on the right) and the
height below the
x-axis (3 in the
pic) and add them together to get the amplitude
(which is 4+3=7
in the pic). |
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Angle
An angle is the set of
points (what is formed) when two rays both start at
the same point. |
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Annual
Annual means yearly or once a
year. The term shows up in a lot of money problems in
algebra. |
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Annuity
An annuity is an investment (like
a savings account) where you put in a certain amount each
year or each month. For example, you might invest
$2000 each year into your company's retirement account.
Or you might set up a savings account where you automatically
deposit $100 each month out of your paycheck.
For more info on annuities, check out my
annuities lessons over at FinanceFREAK.com. |
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Arc
An arc of a
circle is a
segment of the circumference
of the circle. |
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Area
Wow, you wouldn't believe how confusing the usual
definitions for "area" in math dictionaries are!
And it's such a simple thing. So, here's my
explanation: If you are going to carpet a
room, the amount of carpet you need IS the area.
In the picture on the right, the area is the
blue part.
For more info on areas, check out my
reference page on area formulas. |
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Arithmetic
Working with numbers, arithmetic is the process and study of
addition, subtraction, multiplication and division. |
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Associative
Property of Addition
The associative property of addition is a math rule that is
always true. Here it is with letters:
a
+ ( b
+ c
) = ( a
+ b
) + c
Remember that you always do what's in the parenthesis ( )
first. This rule just says that, when you are doing
addition, it doesn't matter which numbers you add
first. You can add the a
and b first OR you can add the
b and c
first and you'll get the same answer. Here it is
with numbers so you can check this for yourself!
2
+ ( 3
+ 4
) = ( 2
+ 3
) +
4
NOTE: This does not work
with subtraction! |
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Associative
Property of Multiplication
The associative property of multiplication is a math rule
that is always true. Here it is with letters:
a
x ( b
x c
) = ( a
x b
) x c
Remember that you always do what's in the parenthesis ( )
first. This rule just says that, when you are doing
multiplication, it doesn't matter which numbers you
multiply first. You can multiply the
a and b
first OR you can multiply the b
and c first and you'll
get the same answer. Here it is with numbers so you
can check this for yourself!
2
x ( 3
x 4
) = ( 2
x 3
) x
4
NOTE: This does not work
with division! |
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Average
This is the same thing as the "mean"
of a group of numbers.
It's weird to define "average" in words, but really easy to show what it is.
Look at this list of numbers: 3,
6, 13, 4, 9... Add them up and we get
35... Now, divide by how
many numbers there are. There are
five numbers, so divide
35 by 5...
We get 7 and that's the average
of this list of numbers. Notice that some of the
numbers are above 7 and some
are below. |
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Axiom
An axiom is a rule in math that is always true.
In fact, it is SO obviously
true that you don't have to prove it's true.
This is an axiom:
The sun rises in the morning.
You know this is true
and I don't have to prove it.
This is not an axiom:
My cat is gold.
Yes,
this is true, but how can you believe me without my
proving it with a picture? Here's proof!
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> |
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Axis of Symmetry
An axis of symmetry is a line that cuts an
object in half so that the two halves are mirror
images of each other. The
yellow lines on the
right are both axes of symmetry. (The plural
of "axis" is "axes.") |
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