Question

Cody read the following statements.

Statement 1: A line segment is a part of a line that has two end points.
Statement 2: A ray is a part of a line that has one endpoint and continues in one direction infinitely.

Which of these options is correct?

• Statement 1 represents a postulate and Statement 2 represents a definition.

• Statement 1 and Statement 2 represent definitions because they explain the meaning of terms.

• Statement 1 represents a definition and Statement 2 represents a theorem.

• Statement 1 and Statement 2 represent postulates because they can be proved.

Answer 1

I can't decide wether their Postulates or Definitions...

Answer 2

if you observe, they are not stating any property or a law

Answer 3

they are just defining, what a "line segement" is, and what a "ray" is

so what do u think they are ?

Answer 4

that sounds like a definition

Answer 5

yep! they both are definition,

you define terms like "line segment", "ray", etc... using undefined terms like, line, plane, point and other defined terms. in geometry, its important to be able to differentiate between these :

1) defined terms
2) undefined terms
3) postulates
4) theorems

Answer 6

thanks! but ive always had trouble distinguishing those....

so undefined terms are like lines and points and are used to define defined terms which, like you said, are like line segments and rays.

but can I ask you what the difference between theorems and postulates is?

Answer 7

you're correct! undefined terms are used to define defined terms.

there are only 3 undefined terms in geometry :
1) point
2) line
3) plane

Answer 8

a postulate tells you about some property. it is a startpoint. it is a observation which we know is true always. we dont attempt to prove it.

a theorem also tells you about some property. but it needs to be proven, using postulates and other proven theorems.

il give you a example. let me think.. .

Answer 9

okay!

Answer 10

can we prove some roses are red ?

Answer 11

can we prove A comes before B in english alphabets ?

Answer 12

first one is a theorem,
second one is a postulate

think why thats true

Answer 13

oh okay i understand!
Thanks so much your a really good teacher!