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Theorem cosadd 11745
Description: Addition formula for cosine. Equation 15 of [Gleason] p. 310. (Contributed by NM, 15-Jan-2006.) (Revised by Mario Carneiro, 30-Apr-2014.)
Assertion
Ref Expression
cosadd ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (cosβ€˜(𝐴 + 𝐡)) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) βˆ’ ((sinβ€˜π΄) Β· (sinβ€˜π΅))))

Proof of Theorem cosadd
StepHypRef Expression
1 addcl 7936 . . 3 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (𝐴 + 𝐡) ∈ β„‚)
2 cosval 11711 . . 3 ((𝐴 + 𝐡) ∈ β„‚ β†’ (cosβ€˜(𝐴 + 𝐡)) = (((expβ€˜(i Β· (𝐴 + 𝐡))) + (expβ€˜(-i Β· (𝐴 + 𝐡)))) / 2))
31, 2syl 14 . 2 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (cosβ€˜(𝐴 + 𝐡)) = (((expβ€˜(i Β· (𝐴 + 𝐡))) + (expβ€˜(-i Β· (𝐴 + 𝐡)))) / 2))
4 coscl 11715 . . . . . . . 8 (𝐴 ∈ β„‚ β†’ (cosβ€˜π΄) ∈ β„‚)
54adantr 276 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (cosβ€˜π΄) ∈ β„‚)
6 coscl 11715 . . . . . . . 8 (𝐡 ∈ β„‚ β†’ (cosβ€˜π΅) ∈ β„‚)
76adantl 277 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (cosβ€˜π΅) ∈ β„‚)
85, 7mulcld 7978 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((cosβ€˜π΄) Β· (cosβ€˜π΅)) ∈ β„‚)
9 ax-icn 7906 . . . . . . . 8 i ∈ β„‚
10 sincl 11714 . . . . . . . . 9 (𝐡 ∈ β„‚ β†’ (sinβ€˜π΅) ∈ β„‚)
1110adantl 277 . . . . . . . 8 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (sinβ€˜π΅) ∈ β„‚)
12 mulcl 7938 . . . . . . . 8 ((i ∈ β„‚ ∧ (sinβ€˜π΅) ∈ β„‚) β†’ (i Β· (sinβ€˜π΅)) ∈ β„‚)
139, 11, 12sylancr 414 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· (sinβ€˜π΅)) ∈ β„‚)
14 sincl 11714 . . . . . . . . 9 (𝐴 ∈ β„‚ β†’ (sinβ€˜π΄) ∈ β„‚)
1514adantr 276 . . . . . . . 8 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (sinβ€˜π΄) ∈ β„‚)
16 mulcl 7938 . . . . . . . 8 ((i ∈ β„‚ ∧ (sinβ€˜π΄) ∈ β„‚) β†’ (i Β· (sinβ€˜π΄)) ∈ β„‚)
179, 15, 16sylancr 414 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· (sinβ€˜π΄)) ∈ β„‚)
1813, 17mulcld 7978 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))) ∈ β„‚)
198, 18addcld 7977 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) ∈ β„‚)
205, 13mulcld 7978 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) ∈ β„‚)
217, 17mulcld 7978 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))) ∈ β„‚)
2220, 21addcld 7977 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄)))) ∈ β„‚)
2319, 22, 19ppncand 8308 . . . 4 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))) + ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) βˆ’ (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄)))))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))))
24 adddi 7943 . . . . . . . 8 ((i ∈ β„‚ ∧ 𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· (𝐴 + 𝐡)) = ((i Β· 𝐴) + (i Β· 𝐡)))
259, 24mp3an1 1324 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· (𝐴 + 𝐡)) = ((i Β· 𝐴) + (i Β· 𝐡)))
2625fveq2d 5520 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (expβ€˜(i Β· (𝐴 + 𝐡))) = (expβ€˜((i Β· 𝐴) + (i Β· 𝐡))))
27 simpl 109 . . . . . . . 8 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ 𝐴 ∈ β„‚)
28 mulcl 7938 . . . . . . . 8 ((i ∈ β„‚ ∧ 𝐴 ∈ β„‚) β†’ (i Β· 𝐴) ∈ β„‚)
299, 27, 28sylancr 414 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· 𝐴) ∈ β„‚)
30 simpr 110 . . . . . . . 8 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ 𝐡 ∈ β„‚)
31 mulcl 7938 . . . . . . . 8 ((i ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· 𝐡) ∈ β„‚)
329, 30, 31sylancr 414 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (i Β· 𝐡) ∈ β„‚)
33 efadd 11683 . . . . . . 7 (((i Β· 𝐴) ∈ β„‚ ∧ (i Β· 𝐡) ∈ β„‚) β†’ (expβ€˜((i Β· 𝐴) + (i Β· 𝐡))) = ((expβ€˜(i Β· 𝐴)) Β· (expβ€˜(i Β· 𝐡))))
3429, 32, 33syl2anc 411 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (expβ€˜((i Β· 𝐴) + (i Β· 𝐡))) = ((expβ€˜(i Β· 𝐴)) Β· (expβ€˜(i Β· 𝐡))))
35 efival 11740 . . . . . . . 8 (𝐴 ∈ β„‚ β†’ (expβ€˜(i Β· 𝐴)) = ((cosβ€˜π΄) + (i Β· (sinβ€˜π΄))))
36 efival 11740 . . . . . . . 8 (𝐡 ∈ β„‚ β†’ (expβ€˜(i Β· 𝐡)) = ((cosβ€˜π΅) + (i Β· (sinβ€˜π΅))))
3735, 36oveqan12d 5894 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((expβ€˜(i Β· 𝐴)) Β· (expβ€˜(i Β· 𝐡))) = (((cosβ€˜π΄) + (i Β· (sinβ€˜π΄))) Β· ((cosβ€˜π΅) + (i Β· (sinβ€˜π΅)))))
385, 17, 7, 13muladdd 8373 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((cosβ€˜π΄) + (i Β· (sinβ€˜π΄))) Β· ((cosβ€˜π΅) + (i Β· (sinβ€˜π΅)))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))))
3937, 38eqtrd 2210 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((expβ€˜(i Β· 𝐴)) Β· (expβ€˜(i Β· 𝐡))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))))
4026, 34, 393eqtrd 2214 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (expβ€˜(i Β· (𝐴 + 𝐡))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))))
41 negicn 8158 . . . . . . . 8 -i ∈ β„‚
42 adddi 7943 . . . . . . . 8 ((-i ∈ β„‚ ∧ 𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-i Β· (𝐴 + 𝐡)) = ((-i Β· 𝐴) + (-i Β· 𝐡)))
4341, 42mp3an1 1324 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-i Β· (𝐴 + 𝐡)) = ((-i Β· 𝐴) + (-i Β· 𝐡)))
4443fveq2d 5520 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (expβ€˜(-i Β· (𝐴 + 𝐡))) = (expβ€˜((-i Β· 𝐴) + (-i Β· 𝐡))))
45 mulcl 7938 . . . . . . . 8 ((-i ∈ β„‚ ∧ 𝐴 ∈ β„‚) β†’ (-i Β· 𝐴) ∈ β„‚)
4641, 27, 45sylancr 414 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-i Β· 𝐴) ∈ β„‚)
47 mulcl 7938 . . . . . . . 8 ((-i ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-i Β· 𝐡) ∈ β„‚)
4841, 30, 47sylancr 414 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-i Β· 𝐡) ∈ β„‚)
49 efadd 11683 . . . . . . 7 (((-i Β· 𝐴) ∈ β„‚ ∧ (-i Β· 𝐡) ∈ β„‚) β†’ (expβ€˜((-i Β· 𝐴) + (-i Β· 𝐡))) = ((expβ€˜(-i Β· 𝐴)) Β· (expβ€˜(-i Β· 𝐡))))
5046, 48, 49syl2anc 411 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (expβ€˜((-i Β· 𝐴) + (-i Β· 𝐡))) = ((expβ€˜(-i Β· 𝐴)) Β· (expβ€˜(-i Β· 𝐡))))
51 efmival 11741 . . . . . . . 8 (𝐴 ∈ β„‚ β†’ (expβ€˜(-i Β· 𝐴)) = ((cosβ€˜π΄) βˆ’ (i Β· (sinβ€˜π΄))))
52 efmival 11741 . . . . . . . 8 (𝐡 ∈ β„‚ β†’ (expβ€˜(-i Β· 𝐡)) = ((cosβ€˜π΅) βˆ’ (i Β· (sinβ€˜π΅))))
5351, 52oveqan12d 5894 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((expβ€˜(-i Β· 𝐴)) Β· (expβ€˜(-i Β· 𝐡))) = (((cosβ€˜π΄) βˆ’ (i Β· (sinβ€˜π΄))) Β· ((cosβ€˜π΅) βˆ’ (i Β· (sinβ€˜π΅)))))
545, 17, 7, 13mulsubd 8374 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((cosβ€˜π΄) βˆ’ (i Β· (sinβ€˜π΄))) Β· ((cosβ€˜π΅) βˆ’ (i Β· (sinβ€˜π΅)))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) βˆ’ (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))))
5553, 54eqtrd 2210 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((expβ€˜(-i Β· 𝐴)) Β· (expβ€˜(-i Β· 𝐡))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) βˆ’ (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))))
5644, 50, 553eqtrd 2214 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (expβ€˜(-i Β· (𝐴 + 𝐡))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) βˆ’ (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))))
5740, 56oveq12d 5893 . . . 4 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((expβ€˜(i Β· (𝐴 + 𝐡))) + (expβ€˜(-i Β· (𝐴 + 𝐡)))) = (((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄))))) + ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) βˆ’ (((cosβ€˜π΄) Β· (i Β· (sinβ€˜π΅))) + ((cosβ€˜π΅) Β· (i Β· (sinβ€˜π΄)))))))
58192timesd 9161 . . . 4 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))) = ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) + (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))))
5923, 57, 583eqtr4d 2220 . . 3 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((expβ€˜(i Β· (𝐴 + 𝐡))) + (expβ€˜(-i Β· (𝐴 + 𝐡)))) = (2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))))
6059oveq1d 5890 . 2 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((expβ€˜(i Β· (𝐴 + 𝐡))) + (expβ€˜(-i Β· (𝐴 + 𝐡)))) / 2) = ((2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))) / 2))
61 2cn 8990 . . . . 5 2 ∈ β„‚
62 2ap0 9012 . . . . 5 2 # 0
63 divcanap3 8655 . . . . 5 (((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) ∈ β„‚ ∧ 2 ∈ β„‚ ∧ 2 # 0) β†’ ((2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))) / 2) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))))
6461, 62, 63mp3an23 1329 . . . 4 ((((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) ∈ β„‚ β†’ ((2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))) / 2) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))))
6519, 64syl 14 . . 3 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))) / 2) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))))
669a1i 9 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ i ∈ β„‚)
6766, 11, 66, 15mul4d 8112 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))) = ((i Β· i) Β· ((sinβ€˜π΅) Β· (sinβ€˜π΄))))
68 ixi 8540 . . . . . . 7 (i Β· i) = -1
6968oveq1i 5885 . . . . . 6 ((i Β· i) Β· ((sinβ€˜π΅) Β· (sinβ€˜π΄))) = (-1 Β· ((sinβ€˜π΅) Β· (sinβ€˜π΄)))
7011, 15mulcomd 7979 . . . . . . 7 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((sinβ€˜π΅) Β· (sinβ€˜π΄)) = ((sinβ€˜π΄) Β· (sinβ€˜π΅)))
7170oveq2d 5891 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-1 Β· ((sinβ€˜π΅) Β· (sinβ€˜π΄))) = (-1 Β· ((sinβ€˜π΄) Β· (sinβ€˜π΅))))
7269, 71eqtrid 2222 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((i Β· i) Β· ((sinβ€˜π΅) Β· (sinβ€˜π΄))) = (-1 Β· ((sinβ€˜π΄) Β· (sinβ€˜π΅))))
7315, 11mulcld 7978 . . . . . 6 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((sinβ€˜π΄) Β· (sinβ€˜π΅)) ∈ β„‚)
7473mulm1d 8367 . . . . 5 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (-1 Β· ((sinβ€˜π΄) Β· (sinβ€˜π΅))) = -((sinβ€˜π΄) Β· (sinβ€˜π΅)))
7567, 72, 743eqtrd 2214 . . . 4 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))) = -((sinβ€˜π΄) Β· (sinβ€˜π΅)))
7675oveq2d 5891 . . 3 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄)))) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + -((sinβ€˜π΄) Β· (sinβ€˜π΅))))
778, 73negsubd 8274 . . 3 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + -((sinβ€˜π΄) Β· (sinβ€˜π΅))) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) βˆ’ ((sinβ€˜π΄) Β· (sinβ€˜π΅))))
7865, 76, 773eqtrd 2214 . 2 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ ((2 Β· (((cosβ€˜π΄) Β· (cosβ€˜π΅)) + ((i Β· (sinβ€˜π΅)) Β· (i Β· (sinβ€˜π΄))))) / 2) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) βˆ’ ((sinβ€˜π΄) Β· (sinβ€˜π΅))))
793, 60, 783eqtrd 2214 1 ((𝐴 ∈ β„‚ ∧ 𝐡 ∈ β„‚) β†’ (cosβ€˜(𝐴 + 𝐡)) = (((cosβ€˜π΄) Β· (cosβ€˜π΅)) βˆ’ ((sinβ€˜π΄) Β· (sinβ€˜π΅))))
Colors of variables: wff set class
Syntax hints:   β†’ wi 4   ∧ wa 104   = wceq 1353   ∈ wcel 2148   class class class wbr 4004  β€˜cfv 5217  (class class class)co 5875  β„‚cc 7809  0cc0 7811  1c1 7812  ici 7813   + caddc 7814   Β· cmul 7816   βˆ’ cmin 8128  -cneg 8129   # cap 8538   / cdiv 8629  2c2 8970  expce 11650  sincsin 11652  cosccos 11653
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 614  ax-in2 615  ax-io 709  ax-5 1447  ax-7 1448  ax-gen 1449  ax-ie1 1493  ax-ie2 1494  ax-8 1504  ax-10 1505  ax-11 1506  ax-i12 1507  ax-bndl 1509  ax-4 1510  ax-17 1526  ax-i9 1530  ax-ial 1534  ax-i5r 1535  ax-13 2150  ax-14 2151  ax-ext 2159  ax-coll 4119  ax-sep 4122  ax-nul 4130  ax-pow 4175  ax-pr 4210  ax-un 4434  ax-setind 4537  ax-iinf 4588  ax-cnex 7902  ax-resscn 7903  ax-1cn 7904  ax-1re 7905  ax-icn 7906  ax-addcl 7907  ax-addrcl 7908  ax-mulcl 7909  ax-mulrcl 7910  ax-addcom 7911  ax-mulcom 7912  ax-addass 7913  ax-mulass 7914  ax-distr 7915  ax-i2m1 7916  ax-0lt1 7917  ax-1rid 7918  ax-0id 7919  ax-rnegex 7920  ax-precex 7921  ax-cnre 7922  ax-pre-ltirr 7923  ax-pre-ltwlin 7924  ax-pre-lttrn 7925  ax-pre-apti 7926  ax-pre-ltadd 7927  ax-pre-mulgt0 7928  ax-pre-mulext 7929  ax-arch 7930  ax-caucvg 7931
This theorem depends on definitions:  df-bi 117  df-dc 835  df-3or 979  df-3an 980  df-tru 1356  df-fal 1359  df-nf 1461  df-sb 1763  df-eu 2029  df-mo 2030  df-clab 2164  df-cleq 2170  df-clel 2173  df-nfc 2308  df-ne 2348  df-nel 2443  df-ral 2460  df-rex 2461  df-reu 2462  df-rmo 2463  df-rab 2464  df-v 2740  df-sbc 2964  df-csb 3059  df-dif 3132  df-un 3134  df-in 3136  df-ss 3143  df-nul 3424  df-if 3536  df-pw 3578  df-sn 3599  df-pr 3600  df-op 3602  df-uni 3811  df-int 3846  df-iun 3889  df-disj 3982  df-br 4005  df-opab 4066  df-mpt 4067  df-tr 4103  df-id 4294  df-po 4297  df-iso 4298  df-iord 4367  df-on 4369  df-ilim 4370  df-suc 4372  df-iom 4591  df-xp 4633  df-rel 4634  df-cnv 4635  df-co 4636  df-dm 4637  df-rn 4638  df-res 4639  df-ima 4640  df-iota 5179  df-fun 5219  df-fn 5220  df-f 5221  df-f1 5222  df-fo 5223  df-f1o 5224  df-fv 5225  df-isom 5226  df-riota 5831  df-ov 5878  df-oprab 5879  df-mpo 5880  df-1st 6141  df-2nd 6142  df-recs 6306  df-irdg 6371  df-frec 6392  df-1o 6417  df-oadd 6421  df-er 6535  df-en 6741  df-dom 6742  df-fin 6743  df-sup 6983  df-pnf 7994  df-mnf 7995  df-xr 7996  df-ltxr 7997  df-le 7998  df-sub 8130  df-neg 8131  df-reap 8532  df-ap 8539  df-div 8630  df-inn 8920  df-2 8978  df-3 8979  df-4 8980  df-n0 9177  df-z 9254  df-uz 9529  df-q 9620  df-rp 9654  df-ico 9894  df-fz 10009  df-fzo 10143  df-seqfrec 10446  df-exp 10520  df-fac 10706  df-bc 10728  df-ihash 10756  df-cj 10851  df-re 10852  df-im 10853  df-rsqrt 11007  df-abs 11008  df-clim 11287  df-sumdc 11362  df-ef 11656  df-sin 11658  df-cos 11659
This theorem is referenced by:  tanaddaplem  11746  tanaddap  11747  cossub  11749  sinmul  11752  cosmul  11753  addcos  11754  subcos  11755  sincossq  11756  cos2t  11758  cos12dec  11775  demoivreALT  11781  cosppi  14242  coshalfpip  14246
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