Question

I really need help with proofs

Answer 1

what is the proof, geometric proof right?

Answer 2

elaborate please

Answer 3

Yeah we have to make a proof chart on Triangle Proportionality Theroem.

Answer 4

@mathaddict4471

Answer 5

@zzr0ck3r

Answer 6

i cant seem to access the link you gave

Answer 7

I know it's acting up

Answer 8

Ah I am not good with geo proofs, sorry.

Answer 9

Just a sec

Answer 10

Still acting

Answer 11

try a diagram on here like draw a picture

Answer 12

You always start out a proof with the given info. (by the way, I think the reason we can't access the link is because we need an account for your school district to be able to enter the site)
Anyways, the Triangle Proof Theorem states that:

Answer 13

Ok, out could you help me make a 2 column proof

Answer 14

So, our given info would be DE is parallel to BC, and the reason would simply be given. Next, because the line segments are parallel, <ADE=<DBC and <AED=<ECB because corresponding angles are congruent.
Then, we can then conclude that triangle ADE is similar to triangle ABC because of AA.
So, because they are similar, then their sides correspond to each other. This means that AB/AD=AC/AE.

I'll continue this later, but for a two-column proof you basically have two columns, one labeled "statement" and another labeled "reason". To construct this, you could just use the statements I made and the reasons I gave.

Answer 15

Anyways, back to what I was saying, we know that AD+DB=AB, and AE+EC=AC (statement) because of the Segment addition postulate (reason).
We previously concluded that AB/AD=AC/AE, so now you could just substitute the values to get:
(AD+DB)/AD=(AE+EC)/AE, which is our statement and substitution would be our reason.
Next, you simplify the equation to get:
(AD/AD)+(DB/AD)=(AE/AE)+(EC/AE), which is our statement and simplification is our reason.

Now, the we know that AD/AD and AE/AE both equal one because of the identity property. So, we would get
1+(DB/AD)=1+(EC/AE). Now, we use subtraction (reason) by subtraction 1 on both sides to get:
DB/AD=EC/AE, which is what the Triangle Proportionality Theorem states. The end :)

Answer 16

Thank you so much, and could you help me with another?

Answer 17

Np and sure :)

Answer 18

A prood chart of the Converse of Triangle Proportionality Theorem.

Answer 19

Ok, so the converse would state that if AD/DB=AE/EC, then DE is parallel to BC. (I will draw the diagram again for the sake of scrolling up and down).

Answer 20

And that would be your given statement

Answer 21

Next, we know that BD/AD+AD/AD=CE/EA+EA/EA because of addition. We can then simplify this to (BC+AD)/AD=(CE+EA)/EA.
Then, we use the Segment Addition Postulate to determine that AD+DB=AB and AE+EC=AC. We can then use substitute AB for AD+DB and AC for AE+EC to get
AB/AD=AC/EA.
We know that <B=<B because of the reflexive property.
So, we can use the fact that the sides are proportional and <B=<B to get the fact that triangle ADE is similar to triangle ABC (this is called the SAS similarity theorem).
Afterwards, we conclude that <ADE is congruent to <ABC because of CPCTC.
Finally, we know that DE is parallel to BC because of the Converse of Corresponding Angles theorem. The end :)

Answer 22

Thank you so much.