dumpling model
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.
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?
Check another version where the faces can be changed individually:
https://www.geogebra.org/m/hdgmkgsa
or this version, focusing on its apex and altitude:
https://www.geogebra.org/m/wdkbbq49