Démontre que les deux triangles bleus à l'intérieur de la figure sont isométriques.

Step 1: In an isosceles trapezoid, the non-parallel sides (legs) are equal in length.

Step 2: Drop perpendiculars from the endpoints of the shorter top base to the longer bottom base, forming two right triangles on either end and a rectangle in the middle.

Step 3: The legs of the trapezoid are the hypotenuses of these right triangles. For the legs to be equal, the right triangles must have equal base lengths (the overhanging segments).

Step 4: The left overhanging segment has length $4 - x$.
The right overhanging segment has length $x$.

Step 5: Set the overhanging segments equal:
$4 - x = x$

Step 6: Add $x$ to both sides:
$4 - x + x = x + x$
$4 = 2x$

Step 7: Divide both sides by $2$:
$x = \frac{4}{2}$
$x = 2$

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