Naming Geometry Elements

zee-f · 2012-08-31 10:05:25

Ok sounds good

Bob · 2012-08-31 10:11:28

#1- C
1. We need two points to define a line. A different way to say this is that if you have two points, you will need at least a line to hold them. In this sense, what do you need at least three points to define?
A- three lines
Ba ray
Can angle or a plane
Da line or an angle
E a line segment
F a point

C is a good answer!

3.E
3. In the figure below(IMG), compare the two rays ry_AB and ry_CD. Which one is longer?
A- ry_CD
B-ry_AB
C-ry_CD because the arrow goes right
D-ry_CD because the points are further apart
E- all rays are the same infinite length
F-ry_AB we just can't see it all

I like your answer

#6- F
6. Consider two lines that intersect in a single point in a plane. How many rays would it take to draw the same picture?
A-3
B-5
C-1
D-2
E-6
F-4

F is correct, well done!

#9- A
9. Plane geometry as we study it now can be traced back to Euclid, and his book The Elements. Go HERE (http://www.greenlion.com/Eu-I-1-7.pdf ) to find out more about that book, and find out what it means when they say "A point is that which has no part." Which of these best sums up that idea:
A-A point has no dimensions, it only defines a place in space
B-Points are only on lines, never by themselves
C-A point is only important if it defines a shape
D-Points are very big
E-Points are very small
F-Points stand alone and have nothing more to them

I also think answer A!

#10- C
10. Imagine you printed out figure 1 and enlarged it with a photocopier, then compared the two figures. Everything would appear larger. Would point B really be larger?
A-Yes, it would become a planet
B-No, because the line it is on would not be bigger
C-Yes, because everything would be bigger
D-No, because a point has no dimensions to enlarge
E-Yes, because point B is on a line segment
F-No, because I think the answer choice should be F

The photocopier makes it bigger, but we must think of the point a dimensionless. So it would not really (in our Euclidean World) be larger.

#18- D
18. If I have a line, do I have a plane?
A. Only if you have an additional point not on the line
B.Only if it is a long line
C.Yes, because lines are big
D.Yes, because a line has an infinite number of points
E.Only if the line has three points on it
F Only if the line has 6 or more points on it

Not D. To make a plane you need a point that is not on the line as well. That is answer ???

19-A
19.If I have three points, do I always have a plane?
A-Yes, because three points are enough
B-Yes, because planes are infinite
C-Only if the points are on the same line
D-No, because all the points may be on the same line
E-No, you might have an angle
F- No, you might have a triangle

Take care here. Three points only make a plane if they are not all in a line. So you should say answer ???

Bob

zee-f · 2012-08-31 10:18:42

Thank you so much for the clues they helped a lot here are my new answers for:

10- D

18- A

19- D

bobbym · 2012-08-31 10:22:30

Hi;

zee-f · 2012-08-31 10:27:36

Thanks guys .

These are the last 4 questions in this lesson they all talk about the same image below

7- B

7. Look at the picture below Imagine that at the intersection of ry_EG and ln_DF we placed a point M. Which of the following most completely describes the new elements have we created?

A- <GMF and ls_EM

B- <GMF, ry_MD and ls_EM

C- four rays

D- one angle

E- ry_MD and ry_MF

F- ry_MG

8- F

8. Imagine you printed out the picture below, enlarged it with a photocopier, and then compared the two figures. Everything would look larger, but many of these things would not actually be larger because they are really infinite. Knowing this, tell me how would ls_BC change? How would ln_DF change? How would ry_EG change? How would <GEH change?

A-ls_BC would be bigger, ln_DF would not be bigger, ry_EG would not be bigger, <GEH would not be bigger

B-All of them would be larger

C-They would get fuzzier looking

D- ls_BC would be bigger, ln_DF would be bigger, and the rest would stay the same

E- ln_DF would be bigger, and ry_EG would be bigger, but th rest would stay the same

F- Nothing would change

14-F
14. In figure 1 above, could ls_BC become a line?

A- Maybe if there's nothing in the way
B-Yes, if we can find another point
C-No, because there aren't enough points
D-Yes, because every line segment can be extended into a line
E- No, because it can't cross ry_EH
F- No because it doesn't have arrows

15.A
15. In figure 1 above, can ry_EH be used to create a line?

A-No, because rays need one endpoint
B-No, because <GEH can't have a line in it
C-Yes, but only if it doesn't make <GEH anymore
D-No, because there aren't enough points
E-Yes, because any two points can be used to make a line
F-Only if you make GE a line as well

Bob · 2012-08-31 10:32:20

7- B
7. Look at the picture below Imagine that at the intersection of ry_EG and ln_DF we placed a point M. Which of the following most completely describes the new elements have we created?
A- <GMF and ls_EM
B- <GMF, ry_MD and ls_EM
C- four rays
D- one angle
E- ry_MD and ry_MF
F- ry_MG

B seems best out of the choices ... but I'd like to add some more facts!

8- F
8. Imagine you printed out the picture below, enlarged it with a photocopier, and then compared the two figures. Everything would look larger, but many of these things would not actually be larger because they are really infinite. Knowing this, tell me how would ls_BC change? How would ln_DF change? How would ry_EG change? How would <GEH change?
A-ls_BC would be bigger, ln_DF would not be bigger, ry_EG would not be bigger, <GEH would not be bigger
B-All of them would be larger
C-They would get fuzzier looking
D- ls_BC would be bigger, ln_DF would be bigger, and the rest would stay the same
E- ln_DF would be bigger, and ry_EG would be bigger, but th rest would stay the same
F- Nothing would change

Line segments get bigger.

14-F
14. In figure 1 above, could ls_BC become a line?
A- Maybe if there's nothing in the way
B-Yes, if we can find another point
C-No, because there aren't enough points
D-Yes, because every line segment can be extended into a line
E- No, because it can't cross ry_EH
F- No because it doesn't have arrows

Not sure as the wording is vague. I would say D, as I'm assuming that "extend into a line" means adding the extra bits of line with arrows.

15.A
15. In figure 1 above, can ry_EH be used to create a line?
A-No, because rays need one endpoint
B-No, because <GEH can't have a line in it
C-Yes, but only if it doesn't make <GEH anymore
D-No, because there aren't enough points
E-Yes, because any two points can be used to make a line
F-Only if you make GE a line as well
I think of a ray as "half a line". So I would extend the ray the other way to make it into a full line. This would be answer ???

Bob

Bob · 2012-08-31 10:35:49

hi bobbym,

Who are you hiding your answers from ?

zee-f: 10, 18 and 19 are now correct!

Bob

zee-f · 2012-08-31 10:40:39

#8- B
14 confused because a line segment needs two points and it cant be larger then these point but a line goes on and on and they uses arrows to say they go on

15- am thinking F

zee-f · 2012-08-31 10:41:39

I meant 8- A

zee-f · 2012-08-31 10:52:04

Hey Bob Bundy,

what were facts you wanted to add?

zee-f · 2012-08-31 10:53:24

*the facts

Bob · 2012-08-31 10:57:10

#8- B I meant 8- A

I think A is correct!

14 confused because a line segment needs two points and it cant be larger then these point but a line goes on and on and they uses arrows to say they go on

I think the correct answer is D

15- am thinking F

F ??? Why do you think you must make another line too?

E looks like the correct answer to me. A ray has a starting point and at least one more point to define the direction of the ray.

So use these points to specify the line.

Bob

zee-f · 2012-08-31 11:12:40

am still really confused on 14, 15, 17

17- B is incorrect I posted that

But for 14, 15 am still stuck I don't get it this lesson can get confusing

zee-f · 2012-08-31 11:20:07

A line goes on and on but the ray has a end point

zee-f · 2012-08-31 11:25:51

so 15 A ? because a ray is in a single direction from an endpoint but a line doesn't have a starting or ending point it keeps going for ever all it need is two points to define it.

Bob · 2012-08-31 11:30:27

It is after midnight here in the UK so I'm going to have to stop after this post and look again in the morning.

I think 17B is correct. I can only think that I am getting tied up in the wrong definition for a ray, a line and a plane. The problem is I have done geometry for many years and never needed to use the term ray, so it is confusing me too.

Have you been given definitions for these terms? If so, post them please.

Now for Q7.

I have made the diagram below with M marked.

I think that adds the following:

ray MG
ray MF
ray MD
line segment EM
line segment MG
angle GMF
angle GMD
angle DME
angle EMF

Bye for now, see you tomorrow.

Bob

zee-f · 2012-08-31 11:41:46

Good night and thank you for alll the help

The definitions they gave me are these

Line Segment:The set of all points that lie between two selected points. Or, the shortest distance between two points.

Line: The entire set of points that lie in a location in one direction or in the opposite direction, at any distance, from a particular point.
Every line contains a line segment, and every line segment can be extended into a line.

Ray
A ray is the set of points lying in a single direction from an endpoint.
In an intuitive way, a ray is ½ of a line, because it continues indefinitely in one direction, but has a definite endpoint in the other direction. To define a ray, you need one endpoint, and then a second point somewhere along the ray (not the same as the endpoint) to define the direction

bobbym · 2012-08-31 11:48:21

Hi Bob;

Who are you hiding your answers from ?

In case she wants to work on it a little more without seeing mine. Also, in case someone else pops in and would like to answer the questions.

On some other forums they insist you hide your answer to any post. That allows other people to post their answers. I know we do not have that many people answering questions but...

zee-f · 2012-08-31 12:00:56

Well after reading the lesson two more times I came up with this

14- I choose D-Yes, because every line segment can be extended into a line

14- Explanation:
Yes ls_BC can become a line because Every line contains a line segment, and every line segment can be extended into a line.

15- I choose A-No, because rays need one endpoint

15- Explanation:
Well as mentioned in the lesson because a ray continues indefinitely in one direction, but has a definite endpoint in the other direction, but a line needs two points to define it but it goes beyond these points it doesn't have a starting or ending point it keeps going forever.

zee-f · 2012-08-31 12:02:43

Now am stuck on #17 B was incorrect when I submitted it to my teacher I still don't get why?

17. If I have an angle, do I have a plane?

A Only if you have an additional point not on the angle
BYes, because any two rays can define a plane
CNo, because there aren't enough points
DYes, because angles are big
E No because rays cannot be extended into lines
F Yes, because that means you have two lines that meet at a single point

zee-f · 2012-08-31 12:12:31

But in the lesson it mentioned that A plane is defined by any of the following:

three points not lying on a line
a line and a point not lying on the line
two lines which intersect in a single point or are parallel

So doesn't that make 17-F because an angle has unites two rays in a single end point so then we have two lines that meet at a single point and two lines which intersect in a single point or are parallel are defined as a plane

zee-f · 2012-08-31 12:14:48

or E because a ray has an end point and a line doesn't

bobbym · 2012-08-31 12:18:22

An angle is two rays with a common endpoint. Try F then as long as the rays are two different ones with a common endpoint.

See you later, going to eat.

zee-f · 2012-08-31 12:28:11

I think am going to try E

17- E-No because rays cannot be extended into lines

17-Explanation:
To have a plane two lines have to intersect in a single point or are parallel. Rays have an end point they cant extend to lines. lines don't have end points to start or end them they just have two points to define them.

Ok enjoy am going to rest to

bobbym · 2012-08-31 12:29:15

I originally had C in post #16. Let me know what they give as the right answer.

Math Is Fun Forum

#26 2012-08-31 10:05:25

Re: Naming Geometry Elements

#27 2012-08-31 10:11:28

Re: Naming Geometry Elements

#28 2012-08-31 10:18:42

Re: Naming Geometry Elements

#29 2012-08-31 10:22:30

Re: Naming Geometry Elements

#30 2012-08-31 10:27:36

Re: Naming Geometry Elements

#31 2012-08-31 10:32:20

Re: Naming Geometry Elements

#32 2012-08-31 10:35:49

Re: Naming Geometry Elements

#33 2012-08-31 10:40:39

Re: Naming Geometry Elements

#34 2012-08-31 10:41:39

Re: Naming Geometry Elements

#35 2012-08-31 10:52:04

Re: Naming Geometry Elements

#36 2012-08-31 10:53:24

Re: Naming Geometry Elements

#37 2012-08-31 10:57:10

Re: Naming Geometry Elements

#38 2012-08-31 11:12:40

Re: Naming Geometry Elements

#39 2012-08-31 11:20:07

Re: Naming Geometry Elements

#40 2012-08-31 11:25:51

Re: Naming Geometry Elements

#41 2012-08-31 11:30:27

Re: Naming Geometry Elements

#42 2012-08-31 11:41:46

Re: Naming Geometry Elements

#43 2012-08-31 11:48:21

Re: Naming Geometry Elements

#44 2012-08-31 12:00:56

Re: Naming Geometry Elements

#45 2012-08-31 12:02:43

Re: Naming Geometry Elements

#46 2012-08-31 12:12:31

Re: Naming Geometry Elements

#47 2012-08-31 12:14:48

Re: Naming Geometry Elements

#48 2012-08-31 12:18:22

Re: Naming Geometry Elements

#49 2012-08-31 12:28:11

Re: Naming Geometry Elements

#50 2012-08-31 12:29:15

Re: Naming Geometry Elements

Board footer