This is a rice dumpling model in the shape of a tetrahedron with 4 faces of isosceles triangles. In the 3D model on the right, you may drag D, E and F to fold faces. [br][br]Imagine where the faces will meet. Make a guess and use the checkboxes to find out more about the shape.

If you drag C on the left, the 4 triangles will be changed but remains congruent. How would you describe, in general, which point on the plane will be the projection of the apex? [br][br]Check another version where the faces can be changed individually:[br]https://www.geogebra.org/m/hdgmkgsa [br][br]or this version, focusing on its apex and altitude:[br]https://www.geogebra.org/m/wdkbbq49