theorem Th47: :: JGRAPH_6:47

for a, b, c, d being Real st a < b & c < d holds
( (LSeg (|[a,c]|,|[a,d]|)) \/ (LSeg (|[a,d]|,|[b,d]|)) is_an_arc_of W-min (rectangle (a,b,c,d)), E-max (rectangle (a,b,c,d)) & (LSeg (|[a,c]|,|[b,c]|)) \/ (LSeg (|[b,c]|,|[b,d]|)) is_an_arc_of E-max (rectangle (a,b,c,d)), W-min (rectangle (a,b,c,d)) )