# Geometry

Ηλεκτρονική - Συσκευές

10 Οκτ 2013 (πριν από 4 χρόνια και 8 μήνες)

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SAT
Formulas, Definitions, and Theorems

Geometry

Similar Triangles:

Corresponding angles are equal in measurement and corresponding
sides are proportional.

Equilateral Triangles:

all three angles measure 60 degrees and all three sides are
congruent.

Ve
rtical angles

>< are congruent.

Supplementary

angles add to 180 degrees.

Complementary

angles add to 90 degrees.

Area of a square:

s^2

Slope of a line:

(Y
2

Y
1
)/(X
2

X
1
) = m

Equation of a line:

y = mx + b, where m is the slope and b is the y
-
interce
pt.

The sum of the
interior angles of a polygon

= (n
-

2) x 180, where n = the number of
sides.

Algebra

Direct Proportionality:

y is directly proportional to x if y = kx, for some constant k.

Inverse Proportionality:

y is inversely proportional to x if

y = k/x, for some constant k.

Factoring the
difference of two squares
: a^2
-

b^2 = (a + b)(a

b)

The
distribution

of (x + y)^2 = x^2 + 2xy + y^2

Converting
exponents to roots
: x^(1/2) = √x and x^(1/3) =
3
√x

Numbers & Operations

Sum of Consecutive Integers:

x + (x+1) + (x+2) + (x+n), where (x+n) represents the last
integer.

Distance

= rate x time

Percents:

a% of n = a/100 x n

Percent Change:

(original amount

new amount)/
original amount x 100%

Rational Number:

a number that can be expressed as a ratio of two integers

Irrational Number:

a number that cannot be precisely expressed as a fraction or decimal
(ex. √2, √3,
Π
)

Domain:

the set of values for which a function is

defined. For the function y = f(x), the
domain is the set of all x values for which f(x) is defined.

Range:

the set of outputs, or results, of the function. For the function y = f(x), the range
is the set of all possible y values.

Statistics/Data Anal
ysis/Probability

Permutation:

The number of ways to organize r out of n different objects (order matters)
= n!/(n
-
r)!

Combination:

The number of combinations of r out of n different objects (order does not
matter) = n!/[(n
-
r)!r!]

Average/mean:

sum of al
l data points/total number of data points