Select three elements of the given triangle (any combination of sides and angles) by clicking on them.
Using these elements try to construct a triangle congruent to the given triangle .
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.
(Note: Position the new triangle in the same general direction as triangle ABC to avoid flipping the triangle when checking.)
Check the construction by creating a duplicate of triangle ABC and dragging it over the constructed triangle. Use the solid vertex to drag and the empty to rotate.
Will all possible combinations of three elements work?
Detailed instructions and videos are available at :http://lima.osu.edu/people/iboyadzhiev/GeoGebra/congruentTrianglesTh.html