- #1

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- 72

## Homework Statement

On the picture, ##ABCD## is a parallelogram, ##(EF) // (AB) ##, and ##(GH) // (BC)##.

The problem is : show that lines ##(EB)##, ##(HD)##, and ##(IC)## either all meet in ##M##, or are parallel.

## Homework Equations

## The Attempt at a Solution

I've solved the problem introducing a coordinate system ##(D,\vec {DG},\vec {DA} )##, but this was the 'last chance' idea. I don't like it too much, it is a little messy, and I suspect there are simple ideas that could be used and that I didn't see. So my demand is rather for insights. How would you solve it ? Thanks !