Geometry Terms, Postulates, Theorems

Set : A collection of objects(elements)

Two ways to list sets : -The list method-Set builder notationex) P is the set of all elements x such that x is a primary number P = {x|x is a primary number}

Subset : If set A contains set B, then B c_ A

Proper subset : Subset that is not the set itself (c)

Intersection : Common elements of two sets

Disjoint Sets : Two sets with nothing in common

Collinear Points : Points that lie on the same line

Noncollinear points : Points that do not lie on the same line

Skew lines : Lines that are not coplanar

Parallel plane : Planes that do not intersect

Plane Postulate : Three distinct noncollinear points lie in exactly one plane

Flat Plane Postulate : If two points lie in a plane, then the line containing these two points lies in the same plane

Two parallel lines : are contained in one and only one plane

Line :

Opposite Rays : Ray BA and BC are opposite rays if and only if B is between A and C

Segment : Set of two points A and B and all the points in between Line Segment AB

Plane Seperation Postulate : Every line divides any plane containing the line into three disjoint sets: the line and two half-planes

Angle : Union of two distinct rays with a common endpoint

Close Curve : A curve that begins & ends at the same point

Simple Curve : A curve that does not intersect itself( unless the starting and ending points coincide)

Arc : A curve that is a subset of a circle

Interior of a circle : The set of all planar points whose distance from the center of the circle is less than the length of the radius

Concave set : A set that is not convex