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 Lines Lines that share a point. Y Lines m and n intersect. Point Y is the point of intersection. m n

Parallel Lines Lines in the same plane that do not intersect; planes that do not intersect. k j Lines k and j are parallel. k || j k || j

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

Plane Undefined Term No thickness Extends indefinitely in all directions Plane ABC Plane W W

Parallel Planes Planes not intersect. Planes R and S are parallel. R S

Collinear Points that are on the same line Collinear Points that are on the same line. A B C Points A,B and C are collinear.

Non-collinear Points that are not on the same line Non-collinear Points that are not on the same line. A B C Points A,B and C are non - collinear.

Coplanar Points Points that lie on the same plane. Points P,Q, and R are coplanar. P Q R S

Non-Coplanar Points Points that do not lie on the same plane. Points P,Q,R and S are non-coplanar. P Q R S

Coplanar Lines Lines that lie on the same plane. Lines x, y are coplanar. x y

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. n m Lines m and n intersect at P. P

Postulate For any two points, there is exactly one line through the points. A B l Line l is the only line through A and B

Postulate For any three noncollinear points, there is exactly one plane through the points. A B C Q Points A, B, and C lie in Plane Q.

Postulate If two lines intersect, then they are coplanar. m n Lines m and n lie in only one plane.

Postulate If 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 X Y Z

Postulate Every line contains at least two points. A B 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.  T T C D  

Postulate If a line and a plane intersect, their intersection is a point or a line. I t X w Y Line t intersects Plane x at I. Line w intersects Plane Y at line w.

Card 7 If two points lie in a plane, then the line containing them lies in the plane. If R and S lie in plane B, then RS lies in plane B. B R SS 

Intersecting Planes Planes that share a line. Planes W and Z intersect. Line k is the line of intersection. W Z k

Card 6 Space contains at least four noncoplanar points.     Points A, B, C, and D are noncoplanar. A BD C

Source math/glossary8.html