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<a href="sin_cos3.html#K4" target="_self">cosh_C</a>  <a href="finseq_4.html#K4">/.</a> <a href="complex1.html#K5">0c</a>  = 
<span class="p1">(<span class="default"><span class="p2">(<span class="default"><a href="sin_cos.html#K18">exp</a> <a href="complex1.html#K5">0c</a> </span>)</span> <a href="complex1.html#K8">+</a> <span class="p2">(<span class="default"><a href="sin_cos.html#K18">exp</a> <span class="p3">(<span class="default"><a href="complex1.html#K10">-</a> <a href="complex1.html#K5">0c</a> </span>)</span></span>)</span></span>)</span> <a href="xcmplx_0.html#K7">/</a> 2
<b>by </b><i><a class="txt" href="sin_cos3.html#E9"><i><font color="Green">Lemma9</font></i></a></i>
<br/>.= 
<span class="p1">(<span class="default">1 <a href="nat_1.html#K1">+</a> 1</span>)</span> <a href="real_1.html#K6">/</a> 2
<b>by </b><i><a class="ref" href="sin_cos3.html#T20" target="_self">Th20</a>, <a class="ref" href="complex1.html#D6">COMPLEX1:def 6</a></i>
<br/>.= 
2 <a href="real_1.html#K6">/</a> 2

<br/>.= 
1

;<br/>
<b>hence </b><a NAME="E2:34"/>
<a href="sin_cos3.html#K4" target="_self">cosh_C</a>  <a href="finseq_4.html#K4">/.</a> <a href="complex1.html#K5">0c</a>  <a href="hidden.html#R1">=</a> 1
 ;<br/>


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