Geometry

The sum of the degree measures of the interior angles of any polygon of n sides is: (n-2)(180)

Regular polygon: a polygon that is both equilateral and equiangular.

The measure of one interior angle of a regular n-gon is: ((n-2)(180))/n

Exterior angle of a polygon: An angle that forms a liberate pair with one of the angles

The sum of the degree measures of the exterior angles of any polygon of n sides, taking one exterior angle at each vertex, is 360°

Transitive Property of Inequality:

If a>b, and b>c, then a>c

Substitution Postulate for Inequalities:

If a>b, and b=c, a>c

Addition Postulate for Inequalities: 

if a>b, and c=d, then a+c>b+d OR

if a>b, and c>d, a+c>b+d

Subtraction Postulate for Inequalities: 

If a>b, and c=d, then a-c>b-d

Multiplication Postulate for Inequalities:

If a>b, and c>0, then ac>bc

Division Postulate for Inequalties: 

If a>b, and c>0, then a/c>b/c

The triangle Inequality:

The sum of the lengths of the two sides of a triangle has to be greater than the third side.

A whole is greater than any of its parts. 

The Trichotomy Postulate: 

If a and b are real numbers, than exactly one of the following relations is true: 

• a<b

• a>b

• a=b