Metamath Proof Explorer


Theorem hphl

Description: If two points are on the same half-line with endpoint on a line, they are on the same half-plane defined by this line. (Contributed by Thierry Arnoux, 9-Aug-2020)

Ref Expression
Hypotheses hpgid.p P = Base G
hpgid.i I = Itv G
hpgid.l L = Line 𝒢 G
hpgid.g φ G 𝒢 Tarski
hpgid.d φ D ran L
hpgid.a φ A P
hpgid.o O = a b | a P D b P D t D t a I b
hphl.k K = hl 𝒢 G
hphl.a φ A D
hphl.b φ B P
hphl.c φ C P
hphl.1 φ ¬ B D
hphl.2 φ B K A C
Assertion hphl φ B hp 𝒢 G D C

Proof

Step Hyp Ref Expression
1 hpgid.p P = Base G
2 hpgid.i I = Itv G
3 hpgid.l L = Line 𝒢 G
4 hpgid.g φ G 𝒢 Tarski
5 hpgid.d φ D ran L
6 hpgid.a φ A P
7 hpgid.o O = a b | a P D b P D t D t a I b
8 hphl.k K = hl 𝒢 G
9 hphl.a φ A D
10 hphl.b φ B P
11 hphl.c φ C P
12 hphl.1 φ ¬ B D
13 hphl.2 φ B K A C
14 1 2 8 10 11 6 4 3 13 hlln φ B C L A
15 14 orcd φ B C L A C = A
16 1 3 2 4 11 6 10 15 colrot2 φ A B L C B = C
17 1 2 3 4 5 10 7 11 9 16 8 colhp φ B hp 𝒢 G D C B K A C ¬ B D
18 13 12 17 mpbir2and φ B hp 𝒢 G D C