This figure shows 3 faces of a tetrahedron, all 3 are right triangles. The fourth face is missing. You may drag point D on the right to fold or unfold these faces. [br][br]What can you tell about the missing face of this tetrahedron? What kind of triangle is it? How do you know?[br][br]If you change the side lengths of these faces (by dragging the green points on the left), what is still true about your description of the missing face?[br]

What does the following note tell you about the faces of this tetrahedron?