Points

• Undefined term

• No length, width, or thickness

• Named with a capital letter

Lines

• Undefined term -- No thickness

• Length that goes on forever in two directions

Naming Lines

Intersecting LinesIntersecting LinesLines that share a point.Lines that share a point.

Y

Lines Lines mm and and nn intersect. intersect. Point Y is the point of intersection.Point Y is the point of intersection.

mn

Parallel LinesParallel LinesLines in the same plane that do not Lines in the same plane that do not intersect; planes that do not intersect; planes that do not intersect.intersect.

k

j

Lines Lines kk and and jj are parallel. are parallel. kk || || jj

Skew LinesSkew Lines Lines that do not lie on the Lines that do not lie on the same plane. (They do not same plane. (They do not intersect and are not intersect and are not parallel.)parallel.)

Plane

• Undefined Term

• No thickness

•Extends indefinitely in all directions

Plane ABC

Plane W

W

Parallel PlanesParallel PlanesPlanes not intersect.Planes not intersect.

PlanesPlanes RR and and SS are parallel.are parallel.

R

S

CollinearCollinearPoints that are on the same linePoints that are on the same line.

A B C

Points A,B and C are collinear.

Non-collinearNon-collinearPoints that are not on the same Points that are not on the same lineline.

A B C

Points A,B and C are non -collinear.

Coplanar PointsCoplanar PointsPoints that lie on the same Points that lie on the same plane.plane.

Points P,Q, and R are coplanar.Points P,Q, and R are coplanar.

PQ

R

S

Non-Coplanar Non-Coplanar PointsPointsPoints that do not lie on Points that do not lie on the same plane.the same plane.

Points P,Q,R and S are non-coplanar.Points P,Q,R and S are non-coplanar.

PQ

R

S

Coplanar LinesCoplanar Lines Lines that lie on the same Lines that lie on the same plane.plane.

Lines Lines xx, , yy are coplanar. are coplanar.

xy

Postulates

Statements that are accepted as true.

Theorems

Statements that are proven to be true.

Postulate

If two lines intersect, their intersection is a point.

nm

Lines m and n intersect at P.

P

Postulate

For any two points, there is exactly one line through the points.

AB

lLine l is the only line through A and B

PostulateFor any three noncollinear points, there is exactly one plane through the points.

AB

CQ

Points A, B, and C lie in Plane Q.

Postulate

If two lines intersect, then they are coplanar.

mn

Lines m and n lie in only one plane.

PostulateIf two planes intersect, their intersection is a line.

Planes W and Z intersect in line k.

W

Z

k

Postulate

Every plane contains at least three noncollinear points.

Plane A contains points X, Y and Z.

A

XY

Z

Postulate

Every line contains at least two points.

AB p

Line p contains points A and B.

Postulate

There is exactly one plane containing a given line and a point not on the line.

Only one plane contains T and CD.

TC D

PostulateIf a line and a plane intersect, their intersection is a point or a line.

I

tX wY

Line t intersects Plane x at I.

Line w intersects Plane Y at line w.

Source

http://www.hbschool.com/glossary/math/glossary8.html