Problem 127
Describe cross sections of the icosahedron or dodecahedron by the plane passing through the center and perpendicular to one of the axes of symmetry.
Problem 128
Do there exist six lines passing through the same point and making congruent angles to each other?
Problem 131
Compute volumes of regular tetrahedron and octahedron with the edge \(a\).
Problem 132
\star\( Prove that the volume of an icosahedron with the edge \)a\( is equal to \)\frac{5}{12}(3+\sqrt{5}) a^{3}$. .
