Select three elements of the given triangle ABC (any combination of sides and angles) by clicking on them. Using these elements try to construct a triangle congruent to the given triangle ABC. The segments can be moved by dragging the solid point; rotated by dragging the empty point; clicking the empty point will construct a circle. The angles can be moved by dragging the thicker side; rotated by dragging the empty point or the vertex; the sides can be extended by dragging the endpoints. If your construction has sides parallel to the corresponding sides of the given triangle, you can check your construction by dragging triangle ABC over the constructed triangle. Will all possible combinations of three elements work? Detailed instructions and videos are available at :http://lima.osu.edu/people/iboyadzhiev/GeoGebra/congruentTrianglesTh.html