Proof of Theorem coseq0negpitopi
| Step | Hyp | Ref
| Expression |
| 1 | | simplr 528 |
. . . . 5
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
(cos‘𝐴) =
0) |
| 2 | | pire 15022 |
. . . . . . . . . . . . 13
⊢ π
∈ ℝ |
| 3 | 2 | renegcli 8288 |
. . . . . . . . . . . 12
⊢ -π
∈ ℝ |
| 4 | 3 | rexri 8084 |
. . . . . . . . . . 11
⊢ -π
∈ ℝ* |
| 5 | | elioc2 10011 |
. . . . . . . . . . 11
⊢ ((-π
∈ ℝ* ∧ π ∈ ℝ) → (𝐴 ∈ (-π(,]π) ↔ (𝐴 ∈ ℝ ∧ -π <
𝐴 ∧ 𝐴 ≤ π))) |
| 6 | 4, 2, 5 | mp2an 426 |
. . . . . . . . . 10
⊢ (𝐴 ∈ (-π(,]π) ↔
(𝐴 ∈ ℝ ∧
-π < 𝐴 ∧ 𝐴 ≤ π)) |
| 7 | 6 | simp1bi 1014 |
. . . . . . . . 9
⊢ (𝐴 ∈ (-π(,]π) →
𝐴 ∈
ℝ) |
| 8 | 7 | adantr 276 |
. . . . . . . 8
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
𝐴 ∈
ℝ) |
| 9 | 8 | adantr 276 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ∈
ℝ) |
| 10 | | halfpire 15028 |
. . . . . . . . . 10
⊢ (π /
2) ∈ ℝ |
| 11 | 10 | renegcli 8288 |
. . . . . . . . 9
⊢ -(π /
2) ∈ ℝ |
| 12 | 11 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 2) ∈ ℝ) |
| 13 | | 4re 9067 |
. . . . . . . . . . 11
⊢ 4 ∈
ℝ |
| 14 | | 4ap0 9089 |
. . . . . . . . . . 11
⊢ 4 #
0 |
| 15 | 2, 13, 14 | redivclapi 8806 |
. . . . . . . . . 10
⊢ (π /
4) ∈ ℝ |
| 16 | 15 | renegcli 8288 |
. . . . . . . . 9
⊢ -(π /
4) ∈ ℝ |
| 17 | 16 | a1i 9 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 4) ∈ ℝ) |
| 18 | | 2lt4 9164 |
. . . . . . . . . . 11
⊢ 2 <
4 |
| 19 | | 2re 9060 |
. . . . . . . . . . . . 13
⊢ 2 ∈
ℝ |
| 20 | | 2pos 9081 |
. . . . . . . . . . . . 13
⊢ 0 <
2 |
| 21 | 19, 20 | pm3.2i 272 |
. . . . . . . . . . . 12
⊢ (2 ∈
ℝ ∧ 0 < 2) |
| 22 | | 4pos 9087 |
. . . . . . . . . . . . 13
⊢ 0 <
4 |
| 23 | 13, 22 | pm3.2i 272 |
. . . . . . . . . . . 12
⊢ (4 ∈
ℝ ∧ 0 < 4) |
| 24 | | pipos 15024 |
. . . . . . . . . . . . 13
⊢ 0 <
π |
| 25 | 2, 24 | pm3.2i 272 |
. . . . . . . . . . . 12
⊢ (π
∈ ℝ ∧ 0 < π) |
| 26 | | ltdiv2 8914 |
. . . . . . . . . . . 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 1348 |
. . . . . . . . . . 11
⊢ (2 < 4
↔ (π / 4) < (π / 2)) |
| 28 | 18, 27 | mpbi 145 |
. . . . . . . . . 10
⊢ (π /
4) < (π / 2) |
| 29 | 15, 10 | ltnegi 8520 |
. . . . . . . . . 10
⊢ ((π /
4) < (π / 2) ↔ -(π / 2) < -(π / 4)) |
| 30 | 28, 29 | mpbi 145 |
. . . . . . . . 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 110 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
-(π / 4) < 𝐴) |
| 33 | 12, 17, 9, 31, 32 | lttrd 8152 |
. . . . . . 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 9064 |
. . . . . . . . . 10
⊢ 3 ∈
ℝ |
| 36 | 35, 10 | remulcli 8040 |
. . . . . . . . 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 1016 |
. . . . . . . . 9
⊢ (𝐴 ∈ (-π(,]π) →
𝐴 ≤
π) |
| 39 | 38 | ad2antrr 488 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ≤
π) |
| 40 | | 2lt3 9161 |
. . . . . . . . . . 11
⊢ 2 <
3 |
| 41 | | 3pos 9084 |
. . . . . . . . . . . . 13
⊢ 0 <
3 |
| 42 | 35, 41 | pm3.2i 272 |
. . . . . . . . . . . 12
⊢ (3 ∈
ℝ ∧ 0 < 3) |
| 43 | | ltdiv2 8914 |
. . . . . . . . . . . 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 1348 |
. . . . . . . . . . 11
⊢ (2 < 3
↔ (π / 3) < (π / 2)) |
| 45 | 40, 44 | mpbi 145 |
. . . . . . . . . 10
⊢ (π /
3) < (π / 2) |
| 46 | | ltdivmul 8903 |
. . . . . . . . . . 11
⊢ ((π
∈ ℝ ∧ (π / 2) ∈ ℝ ∧ (3 ∈ ℝ ∧ 0
< 3)) → ((π / 3) < (π / 2) ↔ π < (3 · (π
/ 2)))) |
| 47 | 2, 10, 42, 46 | mp3an 1348 |
. . . . . . . . . 10
⊢ ((π /
3) < (π / 2) ↔ π < (3 · (π / 2))) |
| 48 | 45, 47 | mpbi 145 |
. . . . . . . . 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 8151 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 < (3 · (π /
2))) |
| 51 | 11 | rexri 8084 |
. . . . . . . 8
⊢ -(π /
2) ∈ ℝ* |
| 52 | 36 | rexri 8084 |
. . . . . . . 8
⊢ (3
· (π / 2)) ∈ ℝ* |
| 53 | | elioo2 9996 |
. . . . . . . 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 426 |
. . . . . . 7
⊢ (𝐴 ∈ (-(π / 2)(,)(3
· (π / 2))) ↔ (𝐴 ∈ ℝ ∧ -(π / 2) < 𝐴 ∧ 𝐴 < (3 · (π /
2)))) |
| 55 | 9, 33, 50, 54 | syl3anbrc 1183 |
. . . . . 6
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 ∈ (-(π / 2)(,)(3
· (π / 2)))) |
| 56 | | coseq0q4123 15070 |
. . . . . 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 147 |
. . . 4
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
-(π / 4) < 𝐴) →
𝐴 = (π /
2)) |
| 59 | | prid1g 3726 |
. . . . 5
⊢ ((π /
2) ∈ ℝ → (π / 2) ∈ {(π / 2), -(π /
2)}) |
| 60 | | eleq1a 2268 |
. . . . 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 8055 |
. . . . . . 7
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
𝐴 ∈
ℂ) |
| 64 | 63 | adantr 276 |
. . . . . 6
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 ∈
ℂ) |
| 65 | | cosneg 11892 |
. . . . . . . . 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 528 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) →
(cos‘𝐴) =
0) |
| 68 | 66, 67 | eqtrd 2229 |
. . . . . . 7
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) →
(cos‘-𝐴) =
0) |
| 69 | 8 | renegcld 8406 |
. . . . . . . . . 10
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
-𝐴 ∈
ℝ) |
| 70 | 69 | adantr 276 |
. . . . . . . . 9
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 ∈
ℝ) |
| 71 | | 0re 8026 |
. . . . . . . . . . 11
⊢ 0 ∈
ℝ |
| 72 | 71 | a1i 9 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 0 ∈
ℝ) |
| 73 | | simpr 110 |
. . . . . . . . . . 11
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 < 0) |
| 74 | 8 | adantr 276 |
. . . . . . . . . . . 12
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 ∈
ℝ) |
| 75 | 74 | lt0neg1d 8542 |
. . . . . . . . . . 11
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → (𝐴 < 0 ↔ 0 < -𝐴)) |
| 76 | 73, 75 | mpbid 147 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 0 <
-𝐴) |
| 77 | 72, 70, 76 | ltled 8145 |
. . . . . . . . 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 1015 |
. . . . . . . . . . . . 13
⊢ (𝐴 ∈ (-π(,]π) →
-π < 𝐴) |
| 81 | 80 | adantr 276 |
. . . . . . . . . . . 12
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
-π < 𝐴) |
| 82 | 79, 8, 81 | ltnegcon1d 8552 |
. . . . . . . . . . 11
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
-𝐴 <
π) |
| 83 | 82 | adantr 276 |
. . . . . . . . . 10
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 < π) |
| 84 | 70, 78, 83 | ltled 8145 |
. . . . . . . . 9
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 ≤ π) |
| 85 | 71, 2 | elicc2i 10014 |
. . . . . . . . 9
⊢ (-𝐴 ∈ (0[,]π) ↔
(-𝐴 ∈ ℝ ∧ 0
≤ -𝐴 ∧ -𝐴 ≤ π)) |
| 86 | 70, 77, 84, 85 | syl3anbrc 1183 |
. . . . . . . 8
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 ∈
(0[,]π)) |
| 87 | | coseq00topi 15071 |
. . . . . . . 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 147 |
. . . . . 6
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -𝐴 = (π / 2)) |
| 90 | 64, 89 | negcon1ad 8332 |
. . . . 5
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → -(π /
2) = 𝐴) |
| 91 | 90 | eqcomd 2202 |
. . . 4
⊢ (((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) ∧
𝐴 < 0) → 𝐴 = -(π / 2)) |
| 92 | | prid2g 3727 |
. . . . 5
⊢ (-(π /
2) ∈ ℝ → -(π / 2) ∈ {(π / 2), -(π /
2)}) |
| 93 | | eleq1a 2268 |
. . . . 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 15025 |
. . . . . . 7
⊢ π
∈ ℝ+ |
| 97 | 13, 22 | elrpii 9731 |
. . . . . . 7
⊢ 4 ∈
ℝ+ |
| 98 | | rpdivcl 9754 |
. . . . . . 7
⊢ ((π
∈ ℝ+ ∧ 4 ∈ ℝ+) → (π /
4) ∈ ℝ+) |
| 99 | 96, 97, 98 | mp2an 426 |
. . . . . 6
⊢ (π /
4) ∈ ℝ+ |
| 100 | | rpgt0 9740 |
. . . . . 6
⊢ ((π /
4) ∈ ℝ+ → 0 < (π / 4)) |
| 101 | 99, 100 | ax-mp 5 |
. . . . 5
⊢ 0 <
(π / 4) |
| 102 | | lt0neg2 8496 |
. . . . . 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 145 |
. . . 4
⊢ -(π /
4) < 0 |
| 105 | | axltwlin 8094 |
. . . . 5
⊢ ((-(π
/ 4) ∈ ℝ ∧ 0 ∈ ℝ ∧ 𝐴 ∈ ℝ) → (-(π / 4) < 0
→ (-(π / 4) < 𝐴
∨ 𝐴 <
0))) |
| 106 | 16, 71, 8, 105 | mp3an12i 1352 |
. . . 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 799 |
. 2
⊢ ((𝐴 ∈ (-π(,]π) ∧
(cos‘𝐴) = 0) →
𝐴 ∈ {(π / 2),
-(π / 2)}) |
| 109 | | elpri 3645 |
. . . 4
⊢ (𝐴 ∈ {(π / 2), -(π /
2)} → (𝐴 = (π / 2)
∨ 𝐴 = -(π /
2))) |
| 110 | | fveq2 5558 |
. . . . . 6
⊢ (𝐴 = (π / 2) →
(cos‘𝐴) =
(cos‘(π / 2))) |
| 111 | | coshalfpi 15033 |
. . . . . 6
⊢
(cos‘(π / 2)) = 0 |
| 112 | 110, 111 | eqtrdi 2245 |
. . . . 5
⊢ (𝐴 = (π / 2) →
(cos‘𝐴) =
0) |
| 113 | | fveq2 5558 |
. . . . . 6
⊢ (𝐴 = -(π / 2) →
(cos‘𝐴) =
(cos‘-(π / 2))) |
| 114 | | cosneghalfpi 15034 |
. . . . . 6
⊢
(cos‘-(π / 2)) = 0 |
| 115 | 113, 114 | eqtrdi 2245 |
. . . . 5
⊢ (𝐴 = -(π / 2) →
(cos‘𝐴) =
0) |
| 116 | 112, 115 | jaoi 717 |
. . . 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 277 |
. 2
⊢ ((𝐴 ∈ (-π(,]π) ∧
𝐴 ∈ {(π / 2),
-(π / 2)}) → (cos‘𝐴) = 0) |
| 119 | 108, 118 | impbida 596 |
1
⊢ (𝐴 ∈ (-π(,]π) →
((cos‘𝐴) = 0 ↔
𝐴 ∈ {(π / 2),
-(π / 2)})) |