It really isn't hard to show that such a point exists (by "trihedron" I understand the figure formed by three lines in space, not three rays, as we usually understand).
Ito tunay ay hindi mahirap upang ipakita na tulad ng isang punto umiiral (sa pamamagitan ng "triyedro" Naiintindihan ko ang mga figure nabuo sa pamamagitan ng tatlong linya sa space, hindi tatlong ray, tulad ng karaniwang namin maintindihan).