The sliders are used to determine the measure of two angles in each triangle and the length of a side that is NOT between them.
Points E and F can be slid to close the triangles. Points B and D can be used to rotate the triangles.

What do you notice about the measures of the other sides and angles that are not controlled by the sliders?
What conjecture can you make triangles when two angles are congruent and a side that is not between them?