Euler’s Equation
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Transcript Euler’s Equation
Euler’s Equation
Fr Chris Thiel, OFMCap
St Francis High School
22 Nov 2004
Euler Said:
i
e 1 0
Which is a specific case of
i
e cos isin
But why should we
believe
i
e cos isin ?
Consider These power Series Expansions:
2
3
4
n
x
x
x
x
e 1 x
2! 3! 4!
n!
n 0
x
2
4
6
3
5
7
2n
x
x
x
n x
cos x 1
(1)
2! 4! 6!
2n!
n 0
2n1
x
x
x
x
n
sin x x
(1)
3! 5! 7!
(2n 1)!
n 0
Then…
2
3
4
5
6
x
3 x
4 x
5 x
6 x
e 1 ix i
i
i
i
i
2!
3!
4!
5!
6!
2
3
4
5
6
x
x
x
x
x
e ix 1 ix (1) i (1) i (1)
2!
3!
4!
5!
6!
2
3
4
5
6
7
x
x
x
x
x
x
ix
e 1 ix i
i i
2!
3! 4!
5! 6!
7!
ix
2
2
3
4
5
6
8
10
6
7
x
x
x
x
x
x
e 1 ix i
i i
2!
3! 4!
5! 6!
7!
ix
2
4
x
x
x
x
x
e 1
2! 4! 6! 8! 10!
3
5
7
9
11
x
x
x
x
x
ix i i i i i
3!
5!
7!
9!
11!
2
4
6
8
10
x
x
x
x
x
e ix 1
2! 4! 6! 8! 10!
x 3 x 5 x 7 x 9 x11
ix
3! 5! 7! 9! 11!
ix
2
4
6
8
10
x
x
x
x
x
ix
e 1
2! 4! 6! 8! 10!
x 3 x 5 x 7 x 9 x11
ix
3! 5! 7! 9! 11!
e cos x isin x
ix
i
e cos isin
So if
i
e cos isin
e 1 i0
i
i
e 1
i
e 1 0
QED