Proof of Theorem coseq0negpitopi
Step | Hyp | Ref
| Expression |
1 | | simplr 520 |
. . . . 5
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
(cos‘𝐴) =
0) |
2 | | pire 13347 |
. . . . . . . . . . . . 13
⊢ π
∈ ℝ |
3 | 2 | renegcli 8160 |
. . . . . . . . . . . 12
⊢ -π
∈ ℝ |
4 | 3 | rexri 7956 |
. . . . . . . . . . 11
⊢ -π
∈ ℝ* |
5 | | elioc2 9872 |
. . . . . . . . . . 11
⊢ ((-π
∈ ℝ* ∧ π ∈ ℝ) → (𝐴 ∈ (-π(,]π) ↔ (𝐴 ∈ ℝ ∧ -π <
𝐴 ∧ 𝐴 ≤ π))) |
6 | 4, 2, 5 | mp2an 423 |
. . . . . . . . . 10
⊢ (𝐴 ∈ (-π(,]π) ↔
(𝐴 ∈ ℝ ∧
-π < 𝐴 ∧ 𝐴 ≤ π)) |
7 | 6 | simp1bi 1002 |
. . . . . . . . 9
⊢ (𝐴 ∈ (-π(,]π) →
𝐴 ∈
ℝ) |
8 | 7 | adantr 274 |
. . . . . . . 8
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
𝐴 ∈
ℝ) |
9 | 8 | adantr 274 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ∈
ℝ) |
10 | | halfpire 13353 |
. . . . . . . . . 10
⊢ (π /
2) ∈ ℝ |
11 | 10 | renegcli 8160 |
. . . . . . . . 9
⊢ -(π /
2) ∈ ℝ |
12 | 11 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 2) ∈ ℝ) |
13 | | 4re 8934 |
. . . . . . . . . . 11
⊢ 4 ∈
ℝ |
14 | | 4ap0 8956 |
. . . . . . . . . . 11
⊢ 4 #
0 |
15 | 2, 13, 14 | redivclapi 8675 |
. . . . . . . . . 10
⊢ (π /
4) ∈ ℝ |
16 | 15 | renegcli 8160 |
. . . . . . . . 9
⊢ -(π /
4) ∈ ℝ |
17 | 16 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 4) ∈ ℝ) |
18 | | 2lt4 9030 |
. . . . . . . . . . 11
⊢ 2 <
4 |
19 | | 2re 8927 |
. . . . . . . . . . . . 13
⊢ 2 ∈
ℝ |
20 | | 2pos 8948 |
. . . . . . . . . . . . 13
⊢ 0 <
2 |
21 | 19, 20 | pm3.2i 270 |
. . . . . . . . . . . 12
⊢ (2 ∈
ℝ ∧ 0 < 2) |
22 | | 4pos 8954 |
. . . . . . . . . . . . 13
⊢ 0 <
4 |
23 | 13, 22 | pm3.2i 270 |
. . . . . . . . . . . 12
⊢ (4 ∈
ℝ ∧ 0 < 4) |
24 | | pipos 13349 |
. . . . . . . . . . . . 13
⊢ 0 <
π |
25 | 2, 24 | pm3.2i 270 |
. . . . . . . . . . . 12
⊢ (π
∈ ℝ ∧ 0 < π) |
26 | | ltdiv2 8782 |
. . . . . . . . . . . 12
⊢ (((2
∈ ℝ ∧ 0 < 2) ∧ (4 ∈ ℝ ∧ 0 < 4) ∧
(π ∈ ℝ ∧ 0 < π)) → (2 < 4 ↔ (π / 4)
< (π / 2))) |
27 | 21, 23, 25, 26 | mp3an 1327 |
. . . . . . . . . . 11
⊢ (2 < 4
↔ (π / 4) < (π / 2)) |
28 | 18, 27 | mpbi 144 |
. . . . . . . . . 10
⊢ (π /
4) < (π / 2) |
29 | 15, 10 | ltnegi 8391 |
. . . . . . . . . 10
⊢ ((π /
4) < (π / 2) ↔ -(π / 2) < -(π / 4)) |
30 | 28, 29 | mpbi 144 |
. . . . . . . . 9
⊢ -(π /
2) < -(π / 4) |
31 | 30 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 2) < -(π / 4)) |
32 | | simpr 109 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 4) < 𝐴) |
33 | 12, 17, 9, 31, 32 | lttrd 8024 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 2) < 𝐴) |
34 | 2 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
π ∈ ℝ) |
35 | | 3re 8931 |
. . . . . . . . . 10
⊢ 3 ∈
ℝ |
36 | 35, 10 | remulcli 7913 |
. . . . . . . . 9
⊢ (3
· (π / 2)) ∈ ℝ |
37 | 36 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
(3 · (π / 2)) ∈ ℝ) |
38 | 6 | simp3bi 1004 |
. . . . . . . . 9
⊢ (𝐴 ∈ (-π(,]π) →
𝐴 ≤
π) |
39 | 38 | ad2antrr 480 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ≤
π) |
40 | | 2lt3 9027 |
. . . . . . . . . . 11
⊢ 2 <
3 |
41 | | 3pos 8951 |
. . . . . . . . . . . . 13
⊢ 0 <
3 |
42 | 35, 41 | pm3.2i 270 |
. . . . . . . . . . . 12
⊢ (3 ∈
ℝ ∧ 0 < 3) |
43 | | ltdiv2 8782 |
. . . . . . . . . . . 12
⊢ (((2
∈ ℝ ∧ 0 < 2) ∧ (3 ∈ ℝ ∧ 0 < 3) ∧
(π ∈ ℝ ∧ 0 < π)) → (2 < 3 ↔ (π / 3)
< (π / 2))) |
44 | 21, 42, 25, 43 | mp3an 1327 |
. . . . . . . . . . 11
⊢ (2 < 3
↔ (π / 3) < (π / 2)) |
45 | 40, 44 | mpbi 144 |
. . . . . . . . . 10
⊢ (π /
3) < (π / 2) |
46 | | ltdivmul 8771 |
. . . . . . . . . . 11
⊢ ((π
∈ ℝ ∧ (π / 2) ∈ ℝ ∧ (3 ∈ ℝ ∧ 0
< 3)) → ((π / 3) < (π / 2) ↔ π < (3 · (π
/ 2)))) |
47 | 2, 10, 42, 46 | mp3an 1327 |
. . . . . . . . . 10
⊢ ((π /
3) < (π / 2) ↔ π < (3 · (π / 2))) |
48 | 45, 47 | mpbi 144 |
. . . . . . . . 9
⊢ π <
(3 · (π / 2)) |
49 | 48 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
π < (3 · (π / 2))) |
50 | 9, 34, 37, 39, 49 | lelttrd 8023 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 < (3 · (π /
2))) |
51 | 11 | rexri 7956 |
. . . . . . . 8
⊢ -(π /
2) ∈ ℝ* |
52 | 36 | rexri 7956 |
. . . . . . . 8
⊢ (3
· (π / 2)) ∈ ℝ* |
53 | | elioo2 9857 |
. . . . . . . 8
⊢ ((-(π
/ 2) ∈ ℝ* ∧ (3 · (π / 2)) ∈
ℝ*) → (𝐴 ∈ (-(π / 2)(,)(3 · (π /
2))) ↔ (𝐴 ∈
ℝ ∧ -(π / 2) < 𝐴 ∧ 𝐴 < (3 · (π /
2))))) |
54 | 51, 52, 53 | mp2an 423 |
. . . . . . 7
⊢ (𝐴 ∈ (-(π / 2)(,)(3
· (π / 2))) ↔ (𝐴 ∈ ℝ ∧ -(π / 2) < 𝐴 ∧ 𝐴 < (3 · (π /
2)))) |
55 | 9, 33, 50, 54 | syl3anbrc 1171 |
. . . . . 6
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ∈ (-(π / 2)(,)(3
· (π / 2)))) |
56 | | coseq0q4123 13395 |
. . . . . 6
⊢ (𝐴 ∈ (-(π / 2)(,)(3
· (π / 2))) → ((cos‘𝐴) = 0 ↔ 𝐴 = (π / 2))) |
57 | 55, 56 | syl 14 |
. . . . 5
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
((cos‘𝐴) = 0 ↔
𝐴 = (π /
2))) |
58 | 1, 57 | mpbid 146 |
. . . 4
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 = (π /
2)) |
59 | | prid1g 3680 |
. . . . 5
⊢ ((π /
2) ∈ ℝ → (π / 2) ∈ {(π / 2), -(π /
2)}) |
60 | | eleq1a 2238 |
. . . . 5
⊢ ((π /
2) ∈ {(π / 2), -(π / 2)} → (𝐴 = (π / 2) → 𝐴 ∈ {(π / 2), -(π /
2)})) |
61 | 10, 59, 60 | mp2b 8 |
. . . 4
⊢ (𝐴 = (π / 2) → 𝐴 ∈ {(π / 2), -(π /
2)}) |
62 | 58, 61 | syl 14 |
. . 3
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ∈ {(π / 2),
-(π / 2)}) |
63 | 8 | recnd 7927 |
. . . . . . 7
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
𝐴 ∈
ℂ) |
64 | 63 | adantr 274 |
. . . . . 6
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 ∈
ℂ) |
65 | | cosneg 11668 |
. . . . . . . . 9
⊢ (𝐴 ∈ ℂ →
(cos‘-𝐴) =
(cos‘𝐴)) |
66 | 64, 65 | syl 14 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) →
(cos‘-𝐴) =
(cos‘𝐴)) |
67 | | simplr 520 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) →
(cos‘𝐴) =
0) |
68 | 66, 67 | eqtrd 2198 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) →
(cos‘-𝐴) =
0) |
69 | 8 | renegcld 8278 |
. . . . . . . . . 10
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
-𝐴 ∈
ℝ) |
70 | 69 | adantr 274 |
. . . . . . . . 9
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 ∈
ℝ) |
71 | | 0re 7899 |
. . . . . . . . . . 11
⊢ 0 ∈
ℝ |
72 | 71 | a1i 9 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 0 ∈
ℝ) |
73 | | simpr 109 |
. . . . . . . . . . 11
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 < 0) |
74 | 8 | adantr 274 |
. . . . . . . . . . . 12
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 ∈
ℝ) |
75 | 74 | lt0neg1d 8413 |
. . . . . . . . . . 11
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → (𝐴 < 0 ↔ 0 < -𝐴)) |
76 | 73, 75 | mpbid 146 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 0 <
-𝐴) |
77 | 72, 70, 76 | ltled 8017 |
. . . . . . . . 9
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 0 ≤
-𝐴) |
78 | 2 | a1i 9 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → π
∈ ℝ) |
79 | 2 | a1i 9 |
. . . . . . . . . . . 12
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
π ∈ ℝ) |
80 | 6 | simp2bi 1003 |
. . . . . . . . . . . . 13
⊢ (𝐴 ∈ (-π(,]π) →
-π < 𝐴) |
81 | 80 | adantr 274 |
. . . . . . . . . . . 12
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
-π < 𝐴) |
82 | 79, 8, 81 | ltnegcon1d 8423 |
. . . . . . . . . . 11
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
-𝐴 <
π) |
83 | 82 | adantr 274 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 < π) |
84 | 70, 78, 83 | ltled 8017 |
. . . . . . . . 9
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 ≤ π) |
85 | 71, 2 | elicc2i 9875 |
. . . . . . . . 9
⊢ (-𝐴 ∈ (0[,]π) ↔
(-𝐴 ∈ ℝ ∧ 0
≤ -𝐴 ∧ -𝐴 ≤ π)) |
86 | 70, 77, 84, 85 | syl3anbrc 1171 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 ∈
(0[,]π)) |
87 | | coseq00topi 13396 |
. . . . . . . 8
⊢ (-𝐴 ∈ (0[,]π) →
((cos‘-𝐴) = 0 ↔
-𝐴 = (π /
2))) |
88 | 86, 87 | syl 14 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) →
((cos‘-𝐴) = 0 ↔
-𝐴 = (π /
2))) |
89 | 68, 88 | mpbid 146 |
. . . . . 6
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 = (π / 2)) |
90 | 64, 89 | negcon1ad 8204 |
. . . . 5
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -(π /
2) = 𝐴) |
91 | 90 | eqcomd 2171 |
. . . 4
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 = -(π / 2)) |
92 | | prid2g 3681 |
. . . . 5
⊢ (-(π /
2) ∈ ℝ → -(π / 2) ∈ {(π / 2), -(π /
2)}) |
93 | | eleq1a 2238 |
. . . . 5
⊢ (-(π /
2) ∈ {(π / 2), -(π / 2)} → (𝐴 = -(π / 2) → 𝐴 ∈ {(π / 2), -(π /
2)})) |
94 | 11, 92, 93 | mp2b 8 |
. . . 4
⊢ (𝐴 = -(π / 2) → 𝐴 ∈ {(π / 2), -(π /
2)}) |
95 | 91, 94 | syl 14 |
. . 3
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 ∈ {(π / 2), -(π /
2)}) |
96 | | pirp 13350 |
. . . . . . 7
⊢ π
∈ ℝ+ |
97 | 13, 22 | elrpii 9592 |
. . . . . . 7
⊢ 4 ∈
ℝ+ |
98 | | rpdivcl 9615 |
. . . . . . 7
⊢ ((π
∈ ℝ+ ∧ 4 ∈ ℝ+) → (π /
4) ∈ ℝ+) |
99 | 96, 97, 98 | mp2an 423 |
. . . . . 6
⊢ (π /
4) ∈ ℝ+ |
100 | | rpgt0 9601 |
. . . . . 6
⊢ ((π /
4) ∈ ℝ+ → 0 < (π / 4)) |
101 | 99, 100 | ax-mp 5 |
. . . . 5
⊢ 0 <
(π / 4) |
102 | | lt0neg2 8367 |
. . . . . 6
⊢ ((π /
4) ∈ ℝ → (0 < (π / 4) ↔ -(π / 4) <
0)) |
103 | 15, 102 | ax-mp 5 |
. . . . 5
⊢ (0 <
(π / 4) ↔ -(π / 4) < 0) |
104 | 101, 103 | mpbi 144 |
. . . 4
⊢ -(π /
4) < 0 |
105 | | axltwlin 7966 |
. . . . 5
⊢ ((-(π
/ 4) ∈ ℝ ∧ 0 ∈ ℝ ∧ 𝐴 ∈ ℝ) → (-(π / 4) < 0
→ (-(π / 4) < 𝐴
∨ 𝐴 <
0))) |
106 | 16, 71, 8, 105 | mp3an12i 1331 |
. . . 4
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
(-(π / 4) < 0 → (-(π / 4) < 𝐴 ∨ 𝐴 < 0))) |
107 | 104, 106 | mpi 15 |
. . 3
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
(-(π / 4) < 𝐴 ∨
𝐴 < 0)) |
108 | 62, 95, 107 | mpjaodan 788 |
. 2
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
𝐴 ∈ {(π / 2),
-(π / 2)}) |
109 | | elpri 3599 |
. . . 4
⊢ (𝐴 ∈ {(π / 2), -(π /
2)} → (𝐴 = (π / 2)
∨ 𝐴 = -(π /
2))) |
110 | | fveq2 5486 |
. . . . . 6
⊢ (𝐴 = (π / 2) →
(cos‘𝐴) =
(cos‘(π / 2))) |
111 | | coshalfpi 13358 |
. . . . . 6
⊢
(cos‘(π / 2)) = 0 |
112 | 110, 111 | eqtrdi 2215 |
. . . . 5
⊢ (𝐴 = (π / 2) →
(cos‘𝐴) =
0) |
113 | | fveq2 5486 |
. . . . . 6
⊢ (𝐴 = -(π / 2) →
(cos‘𝐴) =
(cos‘-(π / 2))) |
114 | | cosneghalfpi 13359 |
. . . . . 6
⊢
(cos‘-(π / 2)) = 0 |
115 | 113, 114 | eqtrdi 2215 |
. . . . 5
⊢ (𝐴 = -(π / 2) →
(cos‘𝐴) =
0) |
116 | 112, 115 | jaoi 706 |
. . . 4
⊢ ((𝐴 = (π / 2) ∨ 𝐴 = -(π / 2)) →
(cos‘𝐴) =
0) |
117 | 109, 116 | syl 14 |
. . 3
⊢ (𝐴 ∈ {(π / 2), -(π /
2)} → (cos‘𝐴) =
0) |
118 | 117 | adantl 275 |
. 2
⊢ ((𝐴 ∈ (-π(,]π) ∧
𝐴 ∈ {(π / 2),
-(π / 2)}) → (cos‘𝐴) = 0) |
119 | 108, 118 | impbida 586 |
1
⊢ (𝐴 ∈ (-π(,]π) →
((cos‘𝐴) = 0 ↔
𝐴 ∈ {(π / 2),
-(π / 2)})) |