let p be Point of (TOP-REAL 2); for D being compact with_the_max_arc Subset of (TOP-REAL 2) st |[(- 1),0 ]|,|[1,0 ]| realize-max-dist-in D & p in LSeg |[0 ,3]|,(UMP D) holds
(UMP D) `2 <= p `2
let D be compact with_the_max_arc Subset of (TOP-REAL 2); ( |[(- 1),0 ]|,|[1,0 ]| realize-max-dist-in D & p in LSeg |[0 ,3]|,(UMP D) implies (UMP D) `2 <= p `2 )
set x = UMP D;
assume that
A1:
|[(- 1),0 ]|,|[1,0 ]| realize-max-dist-in D
and
A2:
p in LSeg |[0 ,3]|,(UMP D)
; (UMP D) `2 <= p `2
A3:
UMP D in LSeg |[0 ,3]|,(UMP D)
by RLTOPSP1:69;
A4:
LSeg |[0 ,3]|,(UMP D) is vertical
by A1, Th81;
A5:
|[0 ,3]| = |[(|[0 ,3]| `1 ),(|[0 ,3]| `2 )]|
by EUCLID:57;
A6:
UMP D = |[((UMP D) `1 ),((UMP D) `2 )]|
by EUCLID:57;
|[0 ,3]| in LSeg |[0 ,3]|,(UMP D)
by RLTOPSP1:69;
then A7:
|[0 ,3]| `1 = (UMP D) `1
by A3, A4, SPPOL_1:def 3;
(UMP D) `2 <= |[0 ,3]| `2
by A1, Lm21, Th83, JORDAN21:43;
hence
(UMP D) `2 <= p `2
by A2, A5, A6, A7, JGRAPH_6:9; verum