Question Number 157087 by henderson last updated on 19/Oct/21
$$ \\ $$Let ABCD be a tetrahedron, G, G' and G" the centers of gravity of faces ABC, ACD and ADB, I and J the midpoints of edges [BC] and [CD].
1) Show that lines (IJ) and (GG' ) are parallel.
2) Prove that the points G, G' and G" are not aligned.
3) Show that the planes (GG 'G ") and (BCD) are parallel.
1) Show that lines (IJ) and (GG' ) are parallel.
2) Prove that the points G, G' and G" are not aligned.
3) Show that the planes (GG 'G ") and (BCD) are parallel.