The théorème de Thalès calcul triangle and its reciprocal are fundamental geometric principles dealing with similar triangles and parallel lines. This mathematical concept helps establish relationships between proportional segments in intersecting lines and parallel lines.
- The theorem states that when two lines intersect two other lines, corresponding segments are proportional
- Triangles semblables angles égaux is a key condition where two triangles are similar when their angles are equal
- The démonstration réciproque de Thalès proves that when segments are proportional, the lines must be parallel
- Applications include calculating unknown lengths in geometric figures and proving line parallelism
- The theorem works with both direct and reciprocal demonstrations
