[tex]\displaystyle\bf\\\textbf{Oricare 2 drepte concurente determina un plan.}\\\textbf{Avem 4 drepte care au un punct comun.}\\\\\implies~Numarul~de~plane~determinate~(nP)~este:\\\\nP=C_{\b4}^{\b2}=\frac{4\times3}{1\times2}=2\times3=\boxed{\bf6~plane~determinate}[/tex]
