1. anonymous

2. anonymous

can you help me?

3. anonymous

@e.mccormick

4. e.mccormick

OK, so, what are some ways to prove two traingles are congruent? You want one of them as a goal.

5. anonymous

alright

6. e.mccormick

There are 5 ways. sss, sas, asa, aas, and hl. The last only applies in right triangles: http://www.regentsprep.org/regents/math/geometry/gp4/ltriangles.htm You need to move toward one of those. So you need to take what is given and show how it applies to parts of those, then use other rules to fill in mising bits. For example, it says D is the midpoint of AC. By the definiton of a midpoint that means AD = DC. So that means antyhing wih a side might use that.

7. anonymous

okat its starting to make sense but how to do i put that into proof , statements and reasons?

8. e.mccormick

"By definition, a midpoint of a line segment is the point on that line segment that divides the segment two congruent segments." from http://www.regentsprep.org/regents/math/geometry/gcg2/lmidpoint.htm As I said you use the definition of midpoint to prove that one. What other sides can you prove would have the same measure?

9. anonymous

um so i use the definition as my proof? cbd would have the same measurements

10. e.mccormick

You use the "definition of midpoint" for the reason for that one part, ad = dc cbd? Do you mean the angle? I asked about sides at this point.

11. anonymous

im confused on how to do this paper i dont get what your explaining i cant figure it out so i can write it down

12. e.mccormick

Well, like I said, you have only 5 ways you can prove two triangles are congruent. So you must prove each part of one of those 5, then you can prove that 5.

13. anonymous

okay i get that so for proof for the 1st one i put AD = DC

14. e.mccormick

Well, usually you start by listing the given you would use first. So you need "D us midpoint of AC" and "Given" Then for the 2nd one you can use AD = DC, definition of midpoint.

15. anonymous

proof is D is midpoint of Ac wait im so lost uggghhhhhhh how am i ever gonna finish this stupid paper

16. e.mccormick

It is just a couple more. See, there are three sides, right? And SSS is a proof of congruance. In two lines you just proved one side. So, how would you prove a second side?

17. anonymous

i dont know

18. e.mccormick

Well, what ese is given?

19. anonymous

CD?

20. e.mccormick

There are two givens and a diagram: ABC is isosceles D is the midpoint of AC. We already used "D is the midpoint of AC." so what can you get from "ABC is isosceles"

21. anonymous

BC

22. e.mccormick

BC is what?

23. anonymous

BC = AC?

24. anonymous

or A is the midpoint to BC

25. e.mccormick

No. Not BC = AC. Which sides on the diagram have the same mark?

26. e.mccormick

BC and...?

27. anonymous

BA?

28. e.mccormick

Yes. So the 3rd line is ABC is isosceles, given BC = BA, definition of isosceles

29. e.mccormick

Well, 3rd and 4th lines.

30. e.mccormick

OK, so that covers 2 of the sides. One more side and you prove SSS works. So what is the last side you need?

31. anonymous

DB?

32. e.mccormick

Yes. And DB is a shared side! So it is the same thing. There is a tecnical name for this: Reflexive Property of Equality http://www.mathwords.com/r/reflexive_property.htm The reflective property basically says that everything is itself. It is sstupid, but math actually has a rule to prove this! So the 5th line is: DB = DB, Reflexive Property of Equality

33. anonymous

is that it?

34. e.mccormick

One last line. The SSS line. ADB = CDB, SSS

35. anonymous

okay?

36. e.mccormick

And that is it. See, you prove each side, in this case, then say because the sides are = the triangles are =. So you prove each part then the whole. I'll give a plain language example.

37. anonymous

can you write all the lines out in order so first the proof then statements then reasons cause i cant figure out how to write that part

38. anonymous

i know it sounds like a pain but it would help me out

39. e.mccormick

I want to prove I have done my chores. I have a list of do dishes, make bed, and feed cat. I show that my bed is made. I show that the dishes are on the shelves so they mist have been done. I show that the cat bowl is empty... oops. Proves nothing! But I show the cat is happy and not hungry. So I must of fed the cat. All three things are done so the list must have been done. Proof I did my chores. That is what a proof is about. Showing how things have been done and are linked together. The lines for your proof are here, it this post. Just need to copy them in order.

40. anonymous

what?

41. e.mccormick

That is really what proofs are like. Just how you would prove to a parent that you did what you were told to do.

42. anonymous

but what parts do i use to make that proof your not telling me your using english for math and its confusing me .

43. e.mccormick

Well, from the top down in this post, when did I say things would be line(s) in your proof of triangles?

44. anonymous

no where

45. e.mccormick

I did several times...

46. anonymous

maybe but everything you explained is mixed up in different text and im confused and i asked you if you could straighten them out basically because im lost i wouldnt be asking otherwise.

47. e.mccormick

In those

48. anonymous

okay .. can you help me make sure i got these right then?

49. anonymous

so the 1st one is AD = DC as the proof right?

50. e.mccormick

1) D is Midpoint of AC, Given 2) AD = DC, definition of midpoint

51. anonymous

Do you understand how i have to write this paper out as? Proof is one then, statements then, reasons

52. e.mccormick

Yes. That is why I put a comma.

53. e.mccormick

#) statement , reason

54. anonymous

that doesnt make sense there so 3 commas not 2? i need proof as well as statement and reason

55. e.mccormick

$$\begin{array}{lcl} Statements & \qquad & Reasons \\ \hline \text{D is the midpoint of AC} & \qquad & \text{Given} \\ AD = DC & \qquad & \text{Definition of midpoint} \\ \end{array}$$

56. anonymous

57. e.mccormick

Yes. And I am trying to show how it would look when filled out.

58. anonymous

is my proof ABD = CBD

59. anonymous

i know but wheres the proof???

60. e.mccormick

Which is the LAST line. You build up to that.

61. e.mccormick

Those are the first two lines. There are six lines.

62. anonymous

okay can you write out a the lines? ive been trying to write them down and put it together but i cant get em right :/

63. anonymous

ive been working on this paper for days i need to get it done and its just making me upset more and more

64. anonymous

plus i cant figure out what the damn proof is

65. e.mccormick

Those are the only two that were not written out clearly. The first two. The 3rd, 4th, 5th, and 6th are all in that image: http://assets.openstudy.com/updates/attachments/55ef8588e4b0dedaa9edb1a4-e.mccormick-1441830203955-proof.png I did them as: Statment, reason ABC is isosceles, given They are all there.

66. anonymous

but whats the proof what do i write for proof please tell me im going to cry this is ridiculous i cant figure that part out

67. e.mccormick

As I said, it is right there, six lines. All six are typed out.

68. anonymous

k