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Theorem ioo2bl 7851
Description: An open interval of reals in terms of a ball.
Hypothesis
Ref Expression
remet.1 |- D = ((abs o. - ) |` (RR X. RR))
Assertion
Ref Expression
ioo2bl |- ((A e. RR /\ B e. RR /\ A < B) -> (A(,)B) = (((A + B) / 2)( ball ` D)((B - A) / 2)))

Proof of Theorem ioo2bl
StepHypRef Expression
1 remet.1 . . . . . 6 |- D = ((abs o. - ) |` (RR X. RR))
21bl2ioo 7850 . . . . 5 |- ((((B + A) / 2) e. RR /\ ((B - A) / 2) e. RR /\ 0 < ((B - A) / 2)) -> (((B + A) / 2)( ball ` D)((B - A) / 2)) = ((((B + A) / 2) - ((B - A) / 2))(,)(((B + A) / 2) + ((B - A) / 2))))
3 axaddrcl 5244 . . . . . . 7 |- ((B e. RR /\ A e. RR) -> (B + A) e. RR)
4 rehalfclt 5981 . . . . . . 7 |- ((B + A) e. RR -> ((B + A) / 2) e. RR)
53, 4syl 10 . . . . . 6 |- ((B e. RR /\ A e. RR) -> ((B + A) / 2) e. RR)
653adant3 797 . . . . 5 |- ((B e. RR /\ A e. RR /\ A < B) -> ((B + A) / 2) e. RR)
7 resubclt 5410 . . . . . . 7 |- ((B e. RR /\ A e. RR) -> (B - A) e. RR)
8 rehalfclt 5981 . . . . . . 7 |- ((B - A) e. RR -> ((B - A) / 2) e. RR)
97, 8syl 10 . . . . . 6 |- ((B e. RR /\ A e. RR) -> ((B - A) / 2) e. RR)
1093adant3 797 . . . . 5 |- ((B e. RR /\ A e. RR /\ A < B) -> ((B - A) / 2) e. RR)
11 posdift 5627 . . . . . . . 8 |- ((A e. RR /\ B e. RR) -> (A < B <-> 0 < (B - A)))
1211ancoms 436 . . . . . . 7 |- ((B e. RR /\ A e. RR) -> (A < B <-> 0 < (B - A)))
13 halfpos2t 5984 . . . . . . . 8 |- ((B - A) e. RR -> (0 < (B - A) <-> 0 < ((B - A) / 2)))
147, 13syl 10 . . . . . . 7 |- ((B e. RR /\ A e. RR) -> (0 < (B - A) <-> 0 < ((B - A) / 2)))
1512, 14bitrd 526 . . . . . 6 |- ((B e. RR /\ A e. RR) -> (A < B <-> 0 < ((B - A) / 2)))
1615biimp3a 916 . . . . 5 |- ((B e. RR /\ A e. RR /\ A < B) -> 0 < ((B - A) / 2))
172, 6, 10, 16syl3anc 856 . . . 4 |- ((B e. RR /\ A e. RR /\ A < B) -> (((B + A) / 2)( ball ` D)((B - A) / 2)) = ((((B + A) / 2) - ((B - A) / 2))(,)(((B + A) / 2) + ((B - A) / 2))))
18 pnncant 5452 . . . . . . . . . . 11 |- ((B e. CC /\ A e. CC /\ A e. CC) -> ((B + A) - (B - A)) = (A + A))
19183anidm23 881 . . . . . . . . . 10 |- ((B e. CC /\ A e. CC) -> ((B + A) - (B - A)) = (A + A))
20 2timest 5951 . . . . . . . . . . 11 |- (A e. CC -> (2 x. A) = (A + A))
2120adantl 388 . . . . . . . . . 10 |- ((B e. CC /\ A e. CC) -> (2 x. A) = (A + A))
2219, 21eqtr4d 1502 . . . . . . . . 9 |- ((B e. CC /\ A e. CC) -> ((B + A) - (B - A)) = (2 x. A))
2322opreq1d 3960 . . . . . . . 8 |- ((B e. CC /\ A e. CC) -> (((B + A) - (B - A)) / 2) = ((2 x. A) / 2))
24 2cn 5927 . . . . . . . . . 10 |- 2 e. CC
25 2ne0 5937 . . . . . . . . . . 11 |- 2 =/= 0
26 divsubdirt 5731 . . . . . . . . . . 11 |- ((((B + A) e. CC /\ (B - A) e. CC /\ 2 e. CC) /\ 2 =/= 0) -> (((B + A) - (B - A)) / 2) = (((B + A) / 2) - ((B - A) / 2)))
2725, 26mpan2 694 . . . . . . . . . 10 |- (((B + A) e. CC /\ (B - A) e. CC /\ 2 e. CC) -> (((B + A) - (B - A)) / 2) = (((B + A) / 2) - ((B - A) / 2)))
2824, 27mp3an3 902 . . . . . . . . 9 |- (((B + A) e. CC /\ (B - A) e. CC) -> (((B + A) - (B - A)) / 2) = (((B + A) / 2) - ((B - A) / 2)))
29 axaddcl 5243 . . . . . . . . 9 |- ((B e. CC /\ A e. CC) -> (B + A) e. CC)
30 subclt 5339 . . . . . . . . 9 |- ((B e. CC /\ A e. CC) -> (B - A) e. CC)
3128, 29, 30sylanc 471 . . . . . . . 8 |- ((B e. CC /\ A e. CC) -> (((B + A) - (B - A)) / 2) = (((B + A) / 2) - ((B - A) / 2)))
32 divcan3t 5718 . . . . . . . . . 10 |- ((2 e. CC /\ A e. CC /\ 2 =/= 0) -> ((2 x. A) / 2) = A)
3324, 25, 32mp3an13 904 . . . . . . . . 9 |- (A e. CC -> ((2 x. A) / 2) = A)
3433adantl 388 . . . . . . . 8 |- ((B e. CC /\ A e. CC) -> ((2 x. A) / 2) = A)
3523, 31, 343eqtr3d 1507 . . . . . . 7 |- ((B e. CC /\ A e. CC) -> (((B + A) / 2) - ((B - A) / 2)) = A)
36 ppncant 5453 . . . . . . . . . . 11 |- ((B e. CC /\ A e. CC /\ B e. CC) -> ((B + A) + (B - A)) = (B + B))
37363anidm13 880 . . . . . . . . . 10 |- ((B e. CC /\ A e. CC) -> ((B + A) + (B - A)) = (B + B))
38 2timest 5951 . . . . . . . . . . 11 |- (B e. CC -> (2 x. B) = (B + B))
3938adantr 389 . . . . . . . . . 10 |- ((B e. CC /\ A e. CC) -> (2 x. B) = (B + B))
4037, 39eqtr4d 1502 . . . . . . . . 9 |- ((B e. CC /\ A e. CC) -> ((B + A) + (B - A)) = (2 x. B))
4140opreq1d 3960 . . . . . . . 8 |- ((B e. CC /\ A e. CC) -> (((B + A) + (B - A)) / 2) = ((2 x. B) / 2))
42 divdirt 5713 . . . . . . . . . . 11 |- ((((B + A) e. CC /\ (B - A) e. CC /\ 2 e. CC) /\ 2 =/= 0) -> (((B + A) + (B - A)) / 2) = (((B + A) / 2) + ((B - A) / 2)))
4325, 42mpan2 694 . . . . . . . . . 10 |- (((B + A) e. CC /\ (B - A) e. CC /\ 2 e. CC) -> (((B + A) + (B - A)) / 2) = (((B + A) / 2) + ((B - A) / 2)))
4424, 43mp3an3 902 . . . . . . . . 9 |- (((B + A) e. CC /\ (B - A) e. CC) -> (((B + A) + (B - A)) / 2) = (((B + A) / 2) + ((B - A) / 2)))
4544, 29, 30sylanc 471 . . . . . . . 8 |- ((B e. CC /\ A e. CC) -> (((B + A) + (B - A)) / 2) = (((B + A) / 2) + ((B - A) / 2)))
46 divcan3t 5718 . . . . . . . . . 10 |- ((2 e. CC /\ B e. CC /\ 2 =/= 0) -> ((2 x. B) / 2) = B)
4724, 25, 46mp3an13 904 . . . . . . . . 9 |- (B e. CC -> ((2 x. B) / 2) = B)
4847adantr 389 . . . . . . . 8 |- ((B e. CC /\ A e. CC) -> ((2 x. B) / 2) = B)
4941, 45, 483eqtr3d 1507 . . . . . . 7 |- ((B e. CC /\ A e. CC) -> (((B + A) / 2) + ((B - A) / 2)) = B)
5035, 49opreq12d 3963 . . . . . 6 |- ((B e. CC /\ A e. CC) -> ((((B + A) / 2) - ((B - A) / 2))(,)(((B + A) / 2) + ((B - A) / 2))) = (A(,)B))
51 recnt 5285 . . . . . 6 |- (B e. RR -> B e. CC)
52 recnt 5285 . . . . . 6 |- (A e. RR -> A e. CC)
5350, 51, 52syl2an 454 . . . . 5 |- ((B e. RR /\ A e. RR) -> ((((B + A) / 2) - ((B - A) / 2))(,)(((B + A) / 2) + ((B - A) / 2))) = (A(,)B))
54533adant3 797 . . . 4 |- ((B e. RR /\ A e. RR /\ A < B) -> ((((B + A) / 2) - ((B - A) / 2))(,)(((B + A) / 2) + ((B - A) / 2))) = (A(,)B))
5517, 54eqtr2d 1500 . . 3 |- ((B e. RR /\ A e. RR /\ A < B) -> (A(,)B) = (((B + A) / 2)( ball ` D)((B - A) / 2)))
56553com12 835 . 2 |- ((A e. RR /\ B e. RR /\ A < B) -> (A(,)B) = (((B + A) / 2)( ball `