theorem Th38: :: TOPREALA:38

for a, b, r, s being Real st a <= b & r <= s holds
for A being Subset of (Closed-Interval-TSpace (a,b))
for B being Subset of (Closed-Interval-TSpace (r,s)) holds product ((1,2) --> (A,B)) is Subset of (Trectangle (a,b,r,s))