una piramide e una sfera hanno iscritto

timothy6 · Messaggio da **timothy6** » 11 ott 2007, 20:34

A pyramid $ ABCDS $ is given (the base is convex quadrilateral). A sphere is inscribed in this pyramid and it is tangent to side ABCD at point P.
Prove that
$ \angle APB + \angle CPD = 180^{o} $

timothy6 · Messaggio da **timothy6** » 15 ott 2007, 17:39

no ideas at all?? I have one solution but it's horrible and I'll post it after someone else will prove this

timothy6 · Messaggio da **timothy6** » 04 nov 2007, 14:55

no one could do it?

Sepp · Messaggio da **Sepp** » 05 nov 2007, 13:09

timothy6 ha scritto:no ideas at all?? I have one solution but it's horrible and I'll post it after someone else will prove this

If you have one then post it to the Polish Math Olympiad Committee. But hurry up because it is due to 12 Nov!

jordan · Messaggio da **jordan** » 05 nov 2007, 20:05

ci voleva, sei un genio sepp!!!