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authorluccul <luccul@gmail.com>2010-07-04 19:50:41 +0000
committerbnewbold <bnewbold@adelie.robocracy.org>2010-07-04 19:50:41 +0000
commit1db3e56bce88b7d8e99cd18a69a714c817bd5e7d (patch)
treeebc0441fb39445d5ed81fb461cc0ee3a9a3231f7
parentba5b7c03e8bc4ed4f57c52f278152c3fa0c74dd1 (diff)
downloadafterklein-wiki-1db3e56bce88b7d8e99cd18a69a714c817bd5e7d.tar.gz
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more formatting
-rw-r--r--Problem Set 2.page16
1 files changed, 6 insertions, 10 deletions
diff --git a/Problem Set 2.page b/Problem Set 2.page
index c114851..5ba4b65 100644
--- a/Problem Set 2.page
+++ b/Problem Set 2.page
@@ -38,12 +38,10 @@ $\int_0^{2\pi} |\sin^2(x)|^2 dx = \sum |a_n|^2.$
# Solutions
-2. Since
-$$\sin x = \frac{e^{ix}-e^{-ix}}{2}$$,
+2. Since $\sin x = \frac{e^{ix}-e^{-ix}}{2}$,
$$\begin{array}{ccl} \sin^4 x &=& \frac{{( e^{ix}-e^{-ix} )}^4}{16} \\
- &=& \frac{e^{i 4x}+e^{-i 4x}-4 e^{i 2x} -4 e^{-i 2x}+6}{16}$. \end{array} $$
-
+ &=& \frac{e^{i 4x}+e^{-i 4x}-4 e^{i 2x} -4 e^{-i 2x}+6}{16}. \end{array} $$
If we express any periodic function $f(x)$ as
@@ -58,14 +56,12 @@ $$\begin{array}{rcl} a_{-4} = a_{4} &=& \sqrt{2\pi} \times 1/16, \\
Since $a_m = < f_m, f >$ and setting $f(x) = \sin^4(x)$,
-$\int_0^{2\pi} \sin^4(x) dx = <1, f> = \sqrt{2\pi} \times < f_0, f >$
-
-$= \sqrt{2\pi} \times a_0 = \frac{3 \pi}{4}$
-
+$$ \begin{array}{ccl} \int_0^{2\pi} \sin^4(x) dx = <1, f> &=& \sqrt{2\pi} \times < f_0, f > \\
+&=& \sqrt{2\pi} \times a_0 \\
+ &=& \frac{3 \pi}{4} \end{array} $$
-3. Since
-$\sin x = \frac{e^{ix}-e^{-ix}}{2}$,
+3. Since $\sin x = \frac{e^{ix}-e^{-ix}}{2}$,
$\sin^2 x = \frac{e^{i 2x}+e^{-i 2x}-2}{4}$