# Two squares

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Revision as of 10:28, 15 July 2020 by A WASSERMANN (talk | contribs) (Created page with "===Example: Two squares=== Consider two arbitrary squares ''ABCD'' and ''BFGE'' having the vertex ''B'' in common, see figure below. Prove that the straight lines ''AE'' and...")

### Example: Two squares

Consider two arbitrary squares *ABCD* and *BFGE* having the vertex *B* in common, see figure below.
Prove that the straight lines *AE* and *CF* are perpendicular for each such two squares.

(Source: Maria Alessandra Mariotti: Reasoning, proof and proving in mathematics education. Proceedings of the 10th International Congress on Mathematical Education (ICME), 4-11 July, 2004. 2008. Construction by Roman Hašek)

### The JavaScript code

```
(function() {
var board = JXG.JSXGraph.initBoard('box', {boundingbox: [-4, 3, 4, -3]});
var A = board.create('point', [-3, -1], {color: 'blue'}),
B = board.create('point', [0, -1], {color: 'blue'}),
E = board.create('point', [1, -2], {name: 'E', color: 'blue'}),
square1 = board.create('regularpolygon', [A, B, 4], {name: 'Square 1'}),
square2 = board.create('regularpolygon', [B, E, 4], {name: 'Square 2'}),
C = square1.vertices[2],
H = square2.vertices[3],
p = board.create('line', [A, H]),
q = board.create('line', [E, C]);
})();
```