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<b>let </b><font color="Maroon">c<sub>1</sub></font> be  <a href="xreal_0.html#V1">real</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>

<i><font color="Green">E6</font></i>:  <a href="sin_cos2.html#K9">tanh</a> <font color="Maroon">c<sub>1</sub></font> = 
<a href="sin_cos2.html#K7">tanh</a>  <a href="seq_1.html#K2">.</a> <font color="Maroon">c<sub>1</sub></font>
<b>by </b><i><a class="ref" href="sin_cos2.html#D6">SIN_COS2:def 6</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="sin_cos2.html#K1">sinh</a>  <a href="seq_1.html#K2">.</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="real_1.html#K6">/</a> <span class="p1">(<span class="default"><a href="sin_cos2.html#K4">cosh</a>  <a href="seq_1.html#K2">.</a> <font color="Maroon">c<sub>1</sub></font></span>)</span>
<b>by </b><i><a class="ref" href="sin_cos2.html#T17">SIN_COS2:17</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="sin_cos2.html#K3">sinh</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="real_1.html#K6">/</a> <span class="p1">(<span class="default"><a href="sin_cos2.html#K4">cosh</a>  <a href="seq_1.html#K2">.</a> <font color="Maroon">c<sub>1</sub></font></span>)</span>
<b>by </b><i><a class="ref" href="sin_cos2.html#D2">SIN_COS2:def 2</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="sin_cos2.html#K3">sinh</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="real_1.html#K6">/</a> <span class="p1">(<span class="default"><a href="sin_cos2.html#K6">cosh</a> <font color="Maroon">c<sub>1</sub></font></span>)</span>
<b>by </b><i><a class="ref" href="sin_cos2.html#D4">SIN_COS2:def 4</a></i>
;<br/>
 <a href="sin_cos2.html#K9">tanh</a> 0 = 
<a href="sin_cos2.html#K7">tanh</a>  <a href="seq_1.html#K2">.</a> 0
<b>by </b><i><a class="ref" href="sin_cos2.html#D6">SIN_COS2:def 6</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="sin_cos2.html#K1">sinh</a>  <a href="seq_1.html#K2">.</a> 0</span>)</span> <a href="real_1.html#K6">/</a> <span class="p1">(<span class="default"><a href="sin_cos2.html#K4">cosh</a>  <a href="seq_1.html#K2">.</a> 0</span>)</span>
<b>by </b><i><a class="ref" href="sin_cos2.html#T17">SIN_COS2:17</a></i>
<br/>.= 
0
<b>by </b><i><a class="ref" href="sin_cos2.html#T16">SIN_COS2:16</a></i>
;<br/>
<b>hence </b><a NAME="E3:4"/>
(  <a href="sin_cos2.html#K9">tanh</a> <font color="Maroon">c<sub>1</sub></font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><a href="sin_cos2.html#K3">sinh</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> <a href="real_1.html#K6">/</a> <span class="p1">(<span class="default"><a href="sin_cos2.html#K6">cosh</a> <font color="Maroon">c<sub>1</sub></font></span>)</span> &amp;  <a href="sin_cos2.html#K9">tanh</a> 0 <a href="hidden.html#R1">=</a> 0 )
 <b>by </b><i><a class="txt" href="sin_cos8.html#E1:4"><i><font color="Green">E6</font></i></a></i>;<br/>


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