HomeHome Metamath Proof Explorer < Previous   Next >
Related theorems
Unicode version

Theorem efivalt 7389
Description: The exponential function in terms of sine and cosine.
Assertion
Ref Expression
efivalt |- (A e. CC -> (exp` (i x. A)) = ((cos`
A) + (i x. (sin` A))))

Proof of Theorem efivalt
StepHypRef Expression
1 2cn 5927 . . . 4 |- 2 e. CC
2 2ne0 5937 . . . . 5 |- 2 =/= 0
3 divdirt 5713 . . . . 5 |- (((((exp` (i x. A)) + (exp` (-ui x. A))) e. CC /\ ((exp` (i x. A)) - (exp` (-ui x. A))) e. CC /\ 2 e. CC) /\ 2 =/= 0) -> ((((exp` (i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) / 2) = ((((exp`
(i x. A)) + (exp` (-ui x. A))) / 2) + (((exp` (i x. A)) - (exp` (-ui x. A))) / 2)))
42, 3mpan2 694 . . . 4 |- ((((exp`
(i x. A)) + (exp` (-ui x. A))) e. CC /\ ((exp` (i x. A)) - (exp` (-ui x. A))) e. CC /\ 2 e. CC) -> ((((exp`
(i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) / 2) = ((((exp`
(i x. A)) + (exp` (-ui x. A))) / 2) + (((exp` (i x. A)) - (exp` (-ui x. A))) / 2)))
51, 4mp3an3 902 . . 3 |- ((((exp`
(i x. A)) + (exp` (-ui x. A))) e. CC /\ ((exp` (i x. A)) - (exp` (-ui x. A))) e. CC) -> ((((exp`
(i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) / 2) = ((((exp`
(i x. A)) + (exp` (-ui x. A))) / 2) + (((exp` (i x. A)) - (exp` (-ui x. A))) / 2)))
6 axaddcl 5243 . . . 4 |- (((exp` (i x. A)) e. CC /\ (exp` (-ui x. A)) e. CC) -> ((exp` (i x. A)) + (exp` (-ui x. A))) e. CC)
7 axicn 5242 . . . . . 6 |- i e. CC
8 axmulcl 5245 . . . . . 6 |- ((i e. CC /\ A e. CC) -> (i x. A) e. CC)
97, 8mpan 693 . . . . 5 |- (A e. CC -> (i x. A) e. CC)
10 efclt 7254 . . . . 5 |- ((i x. A) e. CC -> (exp` (i x. A)) e. CC)
119, 10syl 10 . . . 4 |- (A e. CC -> (exp` (i x. A)) e. CC)
127negcl 5341 . . . . . 6 |- -ui e. CC
13 axmulcl 5245 . . . . . 6 |- ((-ui e. CC /\ A e. CC) -> (-ui x. A) e. CC)
1412, 13mpan 693 . . . . 5 |- (A e. CC -> (-ui x. A) e. CC)
15 efclt 7254 . . . . 5 |- ((-ui x. A) e. CC -> (exp` (-ui x. A)) e. CC)
1614, 15syl 10 . . . 4 |- (A e. CC -> (exp` (-ui x. A)) e. CC)
176, 11, 16sylanc 471 . . 3 |- (A e. CC -> ((exp` (i x. A)) + (exp` (-ui x. A))) e. CC)
18 subclt 5339 . . . 4 |- (((exp` (i x. A)) e. CC /\ (exp` (-ui x. A)) e. CC) -> ((exp` (i x. A)) - (exp` (-ui x. A))) e. CC)
1918, 11, 16sylanc 471 . . 3 |- (A e. CC -> ((exp` (i x. A)) - (exp` (-ui x. A))) e. CC)
205, 17, 19sylanc 471 . 2 |- (A e. CC -> ((((exp` (i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) / 2) = ((((exp`
(i x. A)) + (exp` (-ui x. A))) / 2) + (((exp` (i x. A)) - (exp` (-ui x. A))) / 2)))
21 pncan3t 5349 . . . . . . 7 |- (((exp` (-ui x. A)) e. CC /\ (exp` (i x. A)) e. CC) -> ((exp` (-ui x. A)) + ((exp` (i x. A)) - (exp` (-ui x. A)))) = (exp` (i x. A)))
2221, 16, 11sylanc 471 . . . . . 6 |- (A e. CC -> ((exp` (-ui x. A)) + ((exp` (i x. A)) - (exp`
(-ui x. A)))) = (exp`
(i x. A)))
2322opreq2d 3961 . . . . 5 |- (A e. CC -> ((exp` (i x. A)) + ((exp` (-ui x. A)) + ((exp` (i x. A)) - (exp`
(-ui x. A))))) = ((exp` (i x. A)) + (exp`
(i x. A))))
24 axaddass 5249 . . . . . 6 |- (((exp` (i x. A)) e. CC /\ (exp` (-ui x. A)) e. CC /\ ((exp`
(i x. A)) - (exp` (-ui x. A))) e. CC) -> (((exp` (i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp`
(-ui x. A)))) = ((exp` (i x. A)) + ((exp`
(-ui x. A)) + ((exp` (i x. A)) - (exp` (-ui x. A))))))
2524, 11, 16, 19syl3anc 856 . . . . 5 |- (A e. CC -> (((exp`
(i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) = ((exp` (i x. A)) + ((exp` (-ui x. A)) + ((exp` (i x. A)) - (exp`
(-ui x. A))))))
26 2timest 5951 . . . . . 6 |- ((exp` (i x. A)) e. CC -> (2 x. (exp` (i x. A))) = ((exp` (i x. A)) + (exp` (i x. A))))
2711, 26syl 10 . . . . 5 |- (A e. CC -> (2 x. (exp` (i x. A))) = ((exp` (i x. A)) + (exp` (i x. A))))
2823, 25, 273eqtr4d 1509 . . . 4 |- (A e. CC -> (((exp`
(i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) = (2 x. (exp` (i x. A))))
2928opreq1d 3960 . . 3 |- (A e. CC -> ((((exp` (i x. A)) + (exp` (-ui x. A))) + ((exp` (i x. A)) - (exp` (-ui x. A)))) / 2) = ((2 x. (exp` (i x. A))) / 2))
30 divcan3t 5718 . . . . 5 |- ((2 e. CC /\ (exp` (i x. A)) e. CC /\ 2 =/= 0) -> ((2 x. (exp`
(i x. A))) / 2) = (exp` (i x. A)))
311, 2, 30mp3an13 904 . . . 4 |- ((exp` (i x. A)) e. CC -> ((2 x. (exp` (i x. A))) / 2) = (exp`
(i x. A)))
3211, 31syl 10 . . 3 |- (A e. CC -> ((2 x. (exp` (i x. A))) / 2) = (exp`
(i x. A)))
3329, 32eqtr2d 1500 . 2 |- (A e. CC -> (exp` (i x. A)) = ((((exp` (i x. A)) + (exp`
(-ui x. A))) + ((exp`
(i x. A)) - (exp` (-ui x. A)))) / 2))
34 cosvalt 7372 . . 3 |- (A e. CC -> (cos` A) = (((exp` (i x. A)) + (exp` (-ui x. A))) / 2))
351, 7mulcl 5293 . . . . . 6 |- (2 x. i) e. CC
36 ine0 5406 . . . . . . . 8 |- i =/= 0
371, 7, 2, 36muln0 5668 . . . . . . 7 |- (2 x. i) =/= 0
38 div12t 5707 . . . . . . 7 |- (((i e. CC /\ ((exp` (i x. A)) - (exp` (-ui x. A))) e. CC /\ (2 x. i) e. CC) /\ (2 x. i) =/= 0) -> (i x. (((exp` (i x. A)) - (exp` (-ui x. A))) / (2 x. i))) = (((exp` (i x. A)) - (exp` (-ui x. A))) x. (i / (2 x. i))))
3937, 38mpan2 694 . . . . . 6 |- ((i e. CC /\ ((exp`
(i x. A)) - (exp` (-ui x. A))) e. CC /\ (2 x. i) e. CC) -> (i x. (((exp` (i x. A)) - (exp`
(-ui x. A