Step |
Hyp |
Ref |
Expression |
1 |
|
oveq2 |
⊢ ( 𝑥 = 1 → ( 2 · 𝑥 ) = ( 2 · 1 ) ) |
2 |
1
|
oveq2d |
⊢ ( 𝑥 = 1 → ( 1 ... ( 2 · 𝑥 ) ) = ( 1 ... ( 2 · 1 ) ) ) |
3 |
2
|
sumeq1d |
⊢ ( 𝑥 = 1 → Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( 2 · 1 ) ) ( cos ‘ ( 𝑛 · π ) ) ) |
4 |
3
|
eqeq1d |
⊢ ( 𝑥 = 1 → ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ↔ Σ 𝑛 ∈ ( 1 ... ( 2 · 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) ) |
5 |
|
oveq2 |
⊢ ( 𝑥 = 𝑦 → ( 2 · 𝑥 ) = ( 2 · 𝑦 ) ) |
6 |
5
|
oveq2d |
⊢ ( 𝑥 = 𝑦 → ( 1 ... ( 2 · 𝑥 ) ) = ( 1 ... ( 2 · 𝑦 ) ) ) |
7 |
6
|
sumeq1d |
⊢ ( 𝑥 = 𝑦 → Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) ) |
8 |
7
|
eqeq1d |
⊢ ( 𝑥 = 𝑦 → ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ↔ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) ) |
9 |
|
oveq2 |
⊢ ( 𝑥 = ( 𝑦 + 1 ) → ( 2 · 𝑥 ) = ( 2 · ( 𝑦 + 1 ) ) ) |
10 |
9
|
oveq2d |
⊢ ( 𝑥 = ( 𝑦 + 1 ) → ( 1 ... ( 2 · 𝑥 ) ) = ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ) |
11 |
10
|
sumeq1d |
⊢ ( 𝑥 = ( 𝑦 + 1 ) → Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ( cos ‘ ( 𝑛 · π ) ) ) |
12 |
11
|
eqeq1d |
⊢ ( 𝑥 = ( 𝑦 + 1 ) → ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ↔ Σ 𝑛 ∈ ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) ) |
13 |
|
oveq2 |
⊢ ( 𝑥 = 𝐾 → ( 2 · 𝑥 ) = ( 2 · 𝐾 ) ) |
14 |
13
|
oveq2d |
⊢ ( 𝑥 = 𝐾 → ( 1 ... ( 2 · 𝑥 ) ) = ( 1 ... ( 2 · 𝐾 ) ) ) |
15 |
14
|
sumeq1d |
⊢ ( 𝑥 = 𝐾 → Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( 2 · 𝐾 ) ) ( cos ‘ ( 𝑛 · π ) ) ) |
16 |
15
|
eqeq1d |
⊢ ( 𝑥 = 𝐾 → ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑥 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ↔ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝐾 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) ) |
17 |
|
ax-1cn |
⊢ 1 ∈ ℂ |
18 |
17
|
2timesi |
⊢ ( 2 · 1 ) = ( 1 + 1 ) |
19 |
18
|
oveq2i |
⊢ ( 1 ... ( 2 · 1 ) ) = ( 1 ... ( 1 + 1 ) ) |
20 |
19
|
sumeq1i |
⊢ Σ 𝑛 ∈ ( 1 ... ( 2 · 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) |
21 |
|
1z |
⊢ 1 ∈ ℤ |
22 |
|
uzid |
⊢ ( 1 ∈ ℤ → 1 ∈ ( ℤ≥ ‘ 1 ) ) |
23 |
21 22
|
ax-mp |
⊢ 1 ∈ ( ℤ≥ ‘ 1 ) |
24 |
23
|
a1i |
⊢ ( ⊤ → 1 ∈ ( ℤ≥ ‘ 1 ) ) |
25 |
|
elfzelz |
⊢ ( 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) → 𝑛 ∈ ℤ ) |
26 |
25
|
zcnd |
⊢ ( 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) → 𝑛 ∈ ℂ ) |
27 |
26
|
adantl |
⊢ ( ( ⊤ ∧ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ) → 𝑛 ∈ ℂ ) |
28 |
|
picn |
⊢ π ∈ ℂ |
29 |
28
|
a1i |
⊢ ( ( ⊤ ∧ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ) → π ∈ ℂ ) |
30 |
27 29
|
mulcld |
⊢ ( ( ⊤ ∧ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ) → ( 𝑛 · π ) ∈ ℂ ) |
31 |
30
|
coscld |
⊢ ( ( ⊤ ∧ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ) → ( cos ‘ ( 𝑛 · π ) ) ∈ ℂ ) |
32 |
|
id |
⊢ ( 𝑛 = ( 1 + 1 ) → 𝑛 = ( 1 + 1 ) ) |
33 |
|
1p1e2 |
⊢ ( 1 + 1 ) = 2 |
34 |
32 33
|
eqtrdi |
⊢ ( 𝑛 = ( 1 + 1 ) → 𝑛 = 2 ) |
35 |
34
|
fvoveq1d |
⊢ ( 𝑛 = ( 1 + 1 ) → ( cos ‘ ( 𝑛 · π ) ) = ( cos ‘ ( 2 · π ) ) ) |
36 |
24 31 35
|
fsump1 |
⊢ ( ⊤ → Σ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = ( Σ 𝑛 ∈ ( 1 ... 1 ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( 2 · π ) ) ) ) |
37 |
36
|
mptru |
⊢ Σ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = ( Σ 𝑛 ∈ ( 1 ... 1 ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( 2 · π ) ) ) |
38 |
|
coscl |
⊢ ( π ∈ ℂ → ( cos ‘ π ) ∈ ℂ ) |
39 |
28 38
|
ax-mp |
⊢ ( cos ‘ π ) ∈ ℂ |
40 |
|
oveq1 |
⊢ ( 𝑛 = 1 → ( 𝑛 · π ) = ( 1 · π ) ) |
41 |
28
|
mulid2i |
⊢ ( 1 · π ) = π |
42 |
40 41
|
eqtrdi |
⊢ ( 𝑛 = 1 → ( 𝑛 · π ) = π ) |
43 |
42
|
fveq2d |
⊢ ( 𝑛 = 1 → ( cos ‘ ( 𝑛 · π ) ) = ( cos ‘ π ) ) |
44 |
43
|
fsum1 |
⊢ ( ( 1 ∈ ℤ ∧ ( cos ‘ π ) ∈ ℂ ) → Σ 𝑛 ∈ ( 1 ... 1 ) ( cos ‘ ( 𝑛 · π ) ) = ( cos ‘ π ) ) |
45 |
21 39 44
|
mp2an |
⊢ Σ 𝑛 ∈ ( 1 ... 1 ) ( cos ‘ ( 𝑛 · π ) ) = ( cos ‘ π ) |
46 |
|
cospi |
⊢ ( cos ‘ π ) = - 1 |
47 |
45 46
|
eqtri |
⊢ Σ 𝑛 ∈ ( 1 ... 1 ) ( cos ‘ ( 𝑛 · π ) ) = - 1 |
48 |
|
cos2pi |
⊢ ( cos ‘ ( 2 · π ) ) = 1 |
49 |
47 48
|
oveq12i |
⊢ ( Σ 𝑛 ∈ ( 1 ... 1 ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( 2 · π ) ) ) = ( - 1 + 1 ) |
50 |
|
neg1cn |
⊢ - 1 ∈ ℂ |
51 |
|
1pneg1e0 |
⊢ ( 1 + - 1 ) = 0 |
52 |
17 50 51
|
addcomli |
⊢ ( - 1 + 1 ) = 0 |
53 |
37 49 52
|
3eqtri |
⊢ Σ 𝑛 ∈ ( 1 ... ( 1 + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 |
54 |
20 53
|
eqtri |
⊢ Σ 𝑛 ∈ ( 1 ... ( 2 · 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 |
55 |
18
|
oveq2i |
⊢ ( ( 2 · 𝑦 ) + ( 2 · 1 ) ) = ( ( 2 · 𝑦 ) + ( 1 + 1 ) ) |
56 |
|
2cnd |
⊢ ( 𝑦 ∈ ℕ → 2 ∈ ℂ ) |
57 |
|
nncn |
⊢ ( 𝑦 ∈ ℕ → 𝑦 ∈ ℂ ) |
58 |
17
|
a1i |
⊢ ( 𝑦 ∈ ℕ → 1 ∈ ℂ ) |
59 |
56 57 58
|
adddid |
⊢ ( 𝑦 ∈ ℕ → ( 2 · ( 𝑦 + 1 ) ) = ( ( 2 · 𝑦 ) + ( 2 · 1 ) ) ) |
60 |
56 57
|
mulcld |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 𝑦 ) ∈ ℂ ) |
61 |
60 58 58
|
addassd |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) = ( ( 2 · 𝑦 ) + ( 1 + 1 ) ) ) |
62 |
55 59 61
|
3eqtr4a |
⊢ ( 𝑦 ∈ ℕ → ( 2 · ( 𝑦 + 1 ) ) = ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) |
63 |
62
|
oveq2d |
⊢ ( 𝑦 ∈ ℕ → ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) = ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) ) |
64 |
63
|
sumeq1d |
⊢ ( 𝑦 ∈ ℕ → Σ 𝑛 ∈ ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) ) |
65 |
64
|
adantr |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → Σ 𝑛 ∈ ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ( cos ‘ ( 𝑛 · π ) ) = Σ 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) ) |
66 |
|
1red |
⊢ ( 𝑦 ∈ ℕ → 1 ∈ ℝ ) |
67 |
|
2re |
⊢ 2 ∈ ℝ |
68 |
67
|
a1i |
⊢ ( 𝑦 ∈ ℕ → 2 ∈ ℝ ) |
69 |
|
nnre |
⊢ ( 𝑦 ∈ ℕ → 𝑦 ∈ ℝ ) |
70 |
68 69
|
remulcld |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 𝑦 ) ∈ ℝ ) |
71 |
70 66
|
readdcld |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) + 1 ) ∈ ℝ ) |
72 |
|
2rp |
⊢ 2 ∈ ℝ+ |
73 |
72
|
a1i |
⊢ ( 𝑦 ∈ ℕ → 2 ∈ ℝ+ ) |
74 |
|
nnrp |
⊢ ( 𝑦 ∈ ℕ → 𝑦 ∈ ℝ+ ) |
75 |
73 74
|
rpmulcld |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 𝑦 ) ∈ ℝ+ ) |
76 |
66 75
|
ltaddrp2d |
⊢ ( 𝑦 ∈ ℕ → 1 < ( ( 2 · 𝑦 ) + 1 ) ) |
77 |
66 71 76
|
ltled |
⊢ ( 𝑦 ∈ ℕ → 1 ≤ ( ( 2 · 𝑦 ) + 1 ) ) |
78 |
|
2z |
⊢ 2 ∈ ℤ |
79 |
78
|
a1i |
⊢ ( 𝑦 ∈ ℕ → 2 ∈ ℤ ) |
80 |
|
nnz |
⊢ ( 𝑦 ∈ ℕ → 𝑦 ∈ ℤ ) |
81 |
79 80
|
zmulcld |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 𝑦 ) ∈ ℤ ) |
82 |
81
|
peano2zd |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) + 1 ) ∈ ℤ ) |
83 |
|
eluz |
⊢ ( ( 1 ∈ ℤ ∧ ( ( 2 · 𝑦 ) + 1 ) ∈ ℤ ) → ( ( ( 2 · 𝑦 ) + 1 ) ∈ ( ℤ≥ ‘ 1 ) ↔ 1 ≤ ( ( 2 · 𝑦 ) + 1 ) ) ) |
84 |
21 82 83
|
sylancr |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · 𝑦 ) + 1 ) ∈ ( ℤ≥ ‘ 1 ) ↔ 1 ≤ ( ( 2 · 𝑦 ) + 1 ) ) ) |
85 |
77 84
|
mpbird |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) + 1 ) ∈ ( ℤ≥ ‘ 1 ) ) |
86 |
|
elfzelz |
⊢ ( 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) → 𝑛 ∈ ℤ ) |
87 |
86
|
zcnd |
⊢ ( 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) → 𝑛 ∈ ℂ ) |
88 |
28
|
a1i |
⊢ ( 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) → π ∈ ℂ ) |
89 |
87 88
|
mulcld |
⊢ ( 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) → ( 𝑛 · π ) ∈ ℂ ) |
90 |
89
|
coscld |
⊢ ( 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) → ( cos ‘ ( 𝑛 · π ) ) ∈ ℂ ) |
91 |
90
|
adantl |
⊢ ( ( 𝑦 ∈ ℕ ∧ 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) ) → ( cos ‘ ( 𝑛 · π ) ) ∈ ℂ ) |
92 |
|
fvoveq1 |
⊢ ( 𝑛 = ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) → ( cos ‘ ( 𝑛 · π ) ) = ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) ) |
93 |
85 91 92
|
fsump1 |
⊢ ( 𝑦 ∈ ℕ → Σ 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = ( Σ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) ) ) |
94 |
93
|
adantr |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → Σ 𝑛 ∈ ( 1 ... ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = ( Σ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) ) ) |
95 |
|
1lt2 |
⊢ 1 < 2 |
96 |
95
|
a1i |
⊢ ( 𝑦 ∈ ℕ → 1 < 2 ) |
97 |
|
2t1e2 |
⊢ ( 2 · 1 ) = 2 |
98 |
|
nnge1 |
⊢ ( 𝑦 ∈ ℕ → 1 ≤ 𝑦 ) |
99 |
66 69 73
|
lemul2d |
⊢ ( 𝑦 ∈ ℕ → ( 1 ≤ 𝑦 ↔ ( 2 · 1 ) ≤ ( 2 · 𝑦 ) ) ) |
100 |
98 99
|
mpbid |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 1 ) ≤ ( 2 · 𝑦 ) ) |
101 |
97 100
|
eqbrtrrid |
⊢ ( 𝑦 ∈ ℕ → 2 ≤ ( 2 · 𝑦 ) ) |
102 |
66 68 70 96 101
|
ltletrd |
⊢ ( 𝑦 ∈ ℕ → 1 < ( 2 · 𝑦 ) ) |
103 |
66 70 102
|
ltled |
⊢ ( 𝑦 ∈ ℕ → 1 ≤ ( 2 · 𝑦 ) ) |
104 |
|
eluz |
⊢ ( ( 1 ∈ ℤ ∧ ( 2 · 𝑦 ) ∈ ℤ ) → ( ( 2 · 𝑦 ) ∈ ( ℤ≥ ‘ 1 ) ↔ 1 ≤ ( 2 · 𝑦 ) ) ) |
105 |
21 81 104
|
sylancr |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) ∈ ( ℤ≥ ‘ 1 ) ↔ 1 ≤ ( 2 · 𝑦 ) ) ) |
106 |
103 105
|
mpbird |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 𝑦 ) ∈ ( ℤ≥ ‘ 1 ) ) |
107 |
|
elfzelz |
⊢ ( 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) → 𝑛 ∈ ℤ ) |
108 |
107
|
zcnd |
⊢ ( 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) → 𝑛 ∈ ℂ ) |
109 |
28
|
a1i |
⊢ ( 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) → π ∈ ℂ ) |
110 |
108 109
|
mulcld |
⊢ ( 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) → ( 𝑛 · π ) ∈ ℂ ) |
111 |
110
|
coscld |
⊢ ( 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) → ( cos ‘ ( 𝑛 · π ) ) ∈ ℂ ) |
112 |
111
|
adantl |
⊢ ( ( 𝑦 ∈ ℕ ∧ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ) → ( cos ‘ ( 𝑛 · π ) ) ∈ ℂ ) |
113 |
|
fvoveq1 |
⊢ ( 𝑛 = ( ( 2 · 𝑦 ) + 1 ) → ( cos ‘ ( 𝑛 · π ) ) = ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) |
114 |
106 112 113
|
fsump1 |
⊢ ( 𝑦 ∈ ℕ → Σ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) = ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) ) |
115 |
33 97
|
eqtr4i |
⊢ ( 1 + 1 ) = ( 2 · 1 ) |
116 |
115
|
a1i |
⊢ ( 𝑦 ∈ ℕ → ( 1 + 1 ) = ( 2 · 1 ) ) |
117 |
116
|
oveq2d |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) + ( 1 + 1 ) ) = ( ( 2 · 𝑦 ) + ( 2 · 1 ) ) ) |
118 |
117 61 59
|
3eqtr4d |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) = ( 2 · ( 𝑦 + 1 ) ) ) |
119 |
118
|
fvoveq1d |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) = ( cos ‘ ( ( 2 · ( 𝑦 + 1 ) ) · π ) ) ) |
120 |
57 58
|
addcld |
⊢ ( 𝑦 ∈ ℕ → ( 𝑦 + 1 ) ∈ ℂ ) |
121 |
28
|
a1i |
⊢ ( 𝑦 ∈ ℕ → π ∈ ℂ ) |
122 |
56 120 121
|
mulassd |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · ( 𝑦 + 1 ) ) · π ) = ( 2 · ( ( 𝑦 + 1 ) · π ) ) ) |
123 |
122
|
oveq1d |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · ( 𝑦 + 1 ) ) · π ) / ( 2 · π ) ) = ( ( 2 · ( ( 𝑦 + 1 ) · π ) ) / ( 2 · π ) ) ) |
124 |
120 121
|
mulcld |
⊢ ( 𝑦 ∈ ℕ → ( ( 𝑦 + 1 ) · π ) ∈ ℂ ) |
125 |
|
0re |
⊢ 0 ∈ ℝ |
126 |
|
pipos |
⊢ 0 < π |
127 |
125 126
|
gtneii |
⊢ π ≠ 0 |
128 |
127
|
a1i |
⊢ ( 𝑦 ∈ ℕ → π ≠ 0 ) |
129 |
73
|
rpne0d |
⊢ ( 𝑦 ∈ ℕ → 2 ≠ 0 ) |
130 |
124 121 56 128 129
|
divcan5d |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · ( ( 𝑦 + 1 ) · π ) ) / ( 2 · π ) ) = ( ( ( 𝑦 + 1 ) · π ) / π ) ) |
131 |
120 121 128
|
divcan4d |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 𝑦 + 1 ) · π ) / π ) = ( 𝑦 + 1 ) ) |
132 |
123 130 131
|
3eqtrd |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · ( 𝑦 + 1 ) ) · π ) / ( 2 · π ) ) = ( 𝑦 + 1 ) ) |
133 |
80
|
peano2zd |
⊢ ( 𝑦 ∈ ℕ → ( 𝑦 + 1 ) ∈ ℤ ) |
134 |
132 133
|
eqeltrd |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · ( 𝑦 + 1 ) ) · π ) / ( 2 · π ) ) ∈ ℤ ) |
135 |
|
peano2cn |
⊢ ( 𝑦 ∈ ℂ → ( 𝑦 + 1 ) ∈ ℂ ) |
136 |
57 135
|
syl |
⊢ ( 𝑦 ∈ ℕ → ( 𝑦 + 1 ) ∈ ℂ ) |
137 |
56 136
|
mulcld |
⊢ ( 𝑦 ∈ ℕ → ( 2 · ( 𝑦 + 1 ) ) ∈ ℂ ) |
138 |
137 121
|
mulcld |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · ( 𝑦 + 1 ) ) · π ) ∈ ℂ ) |
139 |
|
coseq1 |
⊢ ( ( ( 2 · ( 𝑦 + 1 ) ) · π ) ∈ ℂ → ( ( cos ‘ ( ( 2 · ( 𝑦 + 1 ) ) · π ) ) = 1 ↔ ( ( ( 2 · ( 𝑦 + 1 ) ) · π ) / ( 2 · π ) ) ∈ ℤ ) ) |
140 |
138 139
|
syl |
⊢ ( 𝑦 ∈ ℕ → ( ( cos ‘ ( ( 2 · ( 𝑦 + 1 ) ) · π ) ) = 1 ↔ ( ( ( 2 · ( 𝑦 + 1 ) ) · π ) / ( 2 · π ) ) ∈ ℤ ) ) |
141 |
134 140
|
mpbird |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ ( ( 2 · ( 𝑦 + 1 ) ) · π ) ) = 1 ) |
142 |
119 141
|
eqtrd |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) = 1 ) |
143 |
114 142
|
oveq12d |
⊢ ( 𝑦 ∈ ℕ → ( Σ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) ) = ( ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) + 1 ) ) |
144 |
143
|
adantr |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → ( Σ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) ) = ( ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) + 1 ) ) |
145 |
|
simpr |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) |
146 |
60 58 121
|
adddird |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · 𝑦 ) + 1 ) · π ) = ( ( ( 2 · 𝑦 ) · π ) + ( 1 · π ) ) ) |
147 |
60 121
|
mulcld |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) · π ) ∈ ℂ ) |
148 |
41 121
|
eqeltrid |
⊢ ( 𝑦 ∈ ℕ → ( 1 · π ) ∈ ℂ ) |
149 |
147 148
|
addcomd |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · 𝑦 ) · π ) + ( 1 · π ) ) = ( ( 1 · π ) + ( ( 2 · 𝑦 ) · π ) ) ) |
150 |
41
|
a1i |
⊢ ( 𝑦 ∈ ℕ → ( 1 · π ) = π ) |
151 |
56 57
|
mulcomd |
⊢ ( 𝑦 ∈ ℕ → ( 2 · 𝑦 ) = ( 𝑦 · 2 ) ) |
152 |
151
|
oveq1d |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) · π ) = ( ( 𝑦 · 2 ) · π ) ) |
153 |
57 56 121
|
mulassd |
⊢ ( 𝑦 ∈ ℕ → ( ( 𝑦 · 2 ) · π ) = ( 𝑦 · ( 2 · π ) ) ) |
154 |
152 153
|
eqtrd |
⊢ ( 𝑦 ∈ ℕ → ( ( 2 · 𝑦 ) · π ) = ( 𝑦 · ( 2 · π ) ) ) |
155 |
150 154
|
oveq12d |
⊢ ( 𝑦 ∈ ℕ → ( ( 1 · π ) + ( ( 2 · 𝑦 ) · π ) ) = ( π + ( 𝑦 · ( 2 · π ) ) ) ) |
156 |
146 149 155
|
3eqtrd |
⊢ ( 𝑦 ∈ ℕ → ( ( ( 2 · 𝑦 ) + 1 ) · π ) = ( π + ( 𝑦 · ( 2 · π ) ) ) ) |
157 |
156
|
fveq2d |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) = ( cos ‘ ( π + ( 𝑦 · ( 2 · π ) ) ) ) ) |
158 |
|
cosper |
⊢ ( ( π ∈ ℂ ∧ 𝑦 ∈ ℤ ) → ( cos ‘ ( π + ( 𝑦 · ( 2 · π ) ) ) ) = ( cos ‘ π ) ) |
159 |
28 80 158
|
sylancr |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ ( π + ( 𝑦 · ( 2 · π ) ) ) ) = ( cos ‘ π ) ) |
160 |
46
|
a1i |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ π ) = - 1 ) |
161 |
157 159 160
|
3eqtrd |
⊢ ( 𝑦 ∈ ℕ → ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) = - 1 ) |
162 |
161
|
adantr |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) = - 1 ) |
163 |
145 162
|
oveq12d |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) = ( 0 + - 1 ) ) |
164 |
163
|
oveq1d |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → ( ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) + 1 ) = ( ( 0 + - 1 ) + 1 ) ) |
165 |
50
|
addid2i |
⊢ ( 0 + - 1 ) = - 1 |
166 |
165
|
oveq1i |
⊢ ( ( 0 + - 1 ) + 1 ) = ( - 1 + 1 ) |
167 |
166 52
|
eqtri |
⊢ ( ( 0 + - 1 ) + 1 ) = 0 |
168 |
164 167
|
eqtrdi |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → ( ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( 2 · 𝑦 ) + 1 ) · π ) ) ) + 1 ) = 0 ) |
169 |
144 168
|
eqtrd |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → ( Σ 𝑛 ∈ ( 1 ... ( ( 2 · 𝑦 ) + 1 ) ) ( cos ‘ ( 𝑛 · π ) ) + ( cos ‘ ( ( ( ( 2 · 𝑦 ) + 1 ) + 1 ) · π ) ) ) = 0 ) |
170 |
65 94 169
|
3eqtrd |
⊢ ( ( 𝑦 ∈ ℕ ∧ Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) → Σ 𝑛 ∈ ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) |
171 |
170
|
ex |
⊢ ( 𝑦 ∈ ℕ → ( Σ 𝑛 ∈ ( 1 ... ( 2 · 𝑦 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 → Σ 𝑛 ∈ ( 1 ... ( 2 · ( 𝑦 + 1 ) ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) ) |
172 |
4 8 12 16 54 171
|
nnind |
⊢ ( 𝐾 ∈ ℕ → Σ 𝑛 ∈ ( 1 ... ( 2 · 𝐾 ) ) ( cos ‘ ( 𝑛 · π ) ) = 0 ) |