# Erased square

I draw a square on the sand. On each of its sides, I put a stone.

Two days later, the stones didn't move, but the wind has blown away the square.

Could you find again the square, given the stones ?

Solution
### Extensions

Now I put the stones on the

**lines** containing the sides.

Same problem.

Solution
Details

New : The points are replaced by circles touching the square's sides

(That is to construct a square whose sides are tangent to 4 given circles)

And also : the square is replaced by a golden rectangle (ratio of sides = φ = (1 + √5)/2)

Details

### Inverse

Now the inverse problem :

I draw 4 points at the vertices of a square on a paper.
Then I draw 4 lines going through these points.
Unfortunately, the lines having the same colour as the points, I can't see my points anymore !
And of course I didn't draw the square itself...

Could you find it ?

Hint
Details