Anyone @Chirag_Hegde,@Viraam_Rao,@Lalit_Kumar4,@Azimuddin_Sheikh,@Anilkumar_Polasa,. Please take a look.
you just need to pick 3 sides and then pick one point off each side
Thats 3\times 4 \times 5 + 3 \times 4 \times 6 + 3 \times 5 \times 6+ 4 \times 5 \times 6=342
Answer given is 422...which case is missing.??
Hmm they included the vertices of the quadrilateral too
But that would make it 461
Missing case ---
4x5 +6x5 +6x3 +4x3 =80
Total triangles 342 (mentioned above)+80 =422
These are the cases when we selected one vertex of quadrilateral and other two points from sides not including the selected vertex.