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## #1 2005-11-26 22:33:58

Joshua17
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### Hard task! Need help!

- inside angle near the A apex is larger than 180°
- and we know that: AB * CD = AD * BC
- point P is symetrical to point A by the BD line.

Prove that PCB and ACD are equal angles.

Can someone give the solution and explain it to me pleas?? It's important.

## #2 2005-11-29 15:15:29

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### Re: Hard task! Need help!

I'm having trouble visualizing what you mean...we are talking about a concave quadrangle, right?...Then P is outside of the qdrngle?
I'll keep at it and get back to you, but any sort of clarification so that I could make a picture in my head would help.
Else, if you have since solved this, I would love to see your proof.

The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
-Bertrand Russell

## #3 2005-12-02 07:06:49

Joshua17
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### Re: Hard task! Need help!

Yes, i think it's outside but still can't prove it maybe u did?? Veary need it...

## #4 2005-12-02 08:50:08

irspow
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### Re: Hard task! Need help!

I'd give it a stab also, but I too am unable to imagine this figure.  Did you say an INSIDE angle of greater than 180 within a QUADRANGLE?  And did you mean AB*BC = CD*DA?  Sorry, but I am a little confused.

## #5 2005-12-02 12:47:35

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### Re: Hard task! Need help!

Ya...sorry josh...I keep trying to draw different pictures and make something with similar triangles but I cannot visualize...I'll keep at it though...
Have you come up with anything at all?  A picture, even?

The greatest challenge to any thinker is stating the problem in a way that will allow a solution.
-Bertrand Russell

## #6 2005-12-02 13:33:15

ryos
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### Re: Hard task! Need help!

Is this an accurate representation of the problem?

El que pega primero pega dos veces.

## #7 2005-12-03 01:44:48

Joshua17
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### Re: Hard task! Need help!

yeah I think that's the right picture

## #8 2005-12-03 02:18:24

ryos
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### Re: Hard task! Need help!

Except that, isn't it the standard to put the vertex of the angle in the middle of its name? So, would "PCB" and "ACB" both have their vertex at C? That would seem to make it easier to prove that the two are equal.

Don't you love these problems where nobody knows quite what they're asking?

El que pega primero pega dos veces.

## #9 2005-12-03 07:07:43

MathsIsFun

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### Re: Hard task! Need help!

For Posterity: ryos' current signature reads "Yo no puedo enamorarla porque solo con mirarla se me olvida lo que voy a decir..."

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

## #10 2005-12-03 09:28:37

ryos
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### Re: Hard task! Need help!

Cool! What does that mean?

El que pega primero pega dos veces.

## #11 2005-12-03 09:33:06

Flowers4Carlos
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### Re: Hard task! Need help!

it reads "I can't love her because just by looking at her i forget what i'm about to say...."

## #12 2005-12-03 09:38:37

ryos
Power Member

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### Re: Hard task! Need help!

Close. More like, "I can't woo her because whenever I see her I forget what I was about to say..."

Edit: or perhaps even more accurate, "I can't woo her because just looking at her make me forget what I was about to say..."

Last edited by ryos (2005-12-03 09:43:54)

El que pega primero pega dos veces.

## #13 2006-01-12 00:06:14

nicole06
Guest

### Re: Hard task! Need help!

#### Flowers4Carlos wrote:

it reads "I can't love her because just by looking at her i forget what i'm about to say...."

## #14 2006-01-12 00:07:58

nicole06
Guest

### Re: Hard task! Need help!

awww that is so cute you should stay with her

## #15 2006-01-12 00:12:11

KRAYZIE D
Guest

### Re: Hard task! Need help!

AWWWWWW THATS SOO CUTE:)

## #16 2006-01-12 00:13:04

andre3000
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### Re: Hard task! Need help!

#### nicole06 wrote:

awww that is so cute you should stay with her

nicole06
Guest

what up big D

## #18 2006-01-12 00:14:34

KRAYZIE D
Guest

### Re: Hard task! Need help!

NIKKI HEY WHATS UP U ARE SOOO CUTE LOL I LOVE U BUNCHIE BUNCHIE AND THATS A LOT OF LOVE