POSTULATE: A FACT ABOUT GEOMETRY THAT IS ACCEPTED AS TRUE

Postulate 1-1: Two points determine a unique line.

Postulate 1-2: If two distinct lines intersect, then their intersection is a point.

Postulate 1-3: Three noncollinear points determine a unique plane.

ExamplePoints Q, R, S, and T are noncollinear. Name

all of the different lines that can be drawn through these points.

Name the intersection of QR and RS

Q

R

S

T

Point R

QR, QS, QT, RS, RT, and ST

ExampleName all the planes that are represented in

the figure below. Planes

A B

C

D E

F

ABCACDBCEDEFABD

Postulate 1-4: If two distinct planes intersect, then their intersection is a line.

ExampleThe figure shows the intersection of six

planes. Name the intersection of planes CDG and BCD

Name the two planes thatintersect in BA.

A

B D

C H

G

F

E

CD

Planes ABC and ABE

AssignmentWorksheet