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<b>let </b><font color="Maroon">z1</font> be  <a href="xcmplx_0.html#V1">complex</a>  <a href="ordinal1.html#NM1" target="_self">number</a> , <font color="Maroon">z2</font> be  <a href="xcmplx_0.html#V1">complex</a>  <a href="ordinal1.html#NM1" target="_self">number</a> ;<br/>

<b>assume </b><a NAME="E1:18"/>
( <font color="Maroon">z1</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">z2</font> or <font color="Maroon">z1</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">z2</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> 0 )
 ;<br/>

<a NAME="E2:18"/><b>then </b>
<font color="Maroon">z1</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">z2</font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a>  <a href="complex1.html#K5">0c</a> 
 
;<br/>
<a NAME="E3:18"/><b>then </b>
(  <a href="comptrig.html#K1">Arg</a> <span class="p1">(<span class="default"><font color="Maroon">z1</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">z2</font></span>)</span> <a href="xxreal_0.html#R1">&lt;</a>  <a href="sin_cos.html#K35">PI</a>  iff  <a href="comptrig.html#K1">Arg</a> <span class="p1">(<span class="default"><a href="xcmplx_0.html#K4">-</a> <span class="p2">(<span class="default"><font color="Maroon">z1</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">z2</font></span>)</span></span>)</span> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a>  <a href="sin_cos.html#K35">PI</a>  )
 
<b>by </b><i/>;<br/>
<b>hence </b><a NAME="E4:18"/>
(  <a href="comptrig.html#K1">Arg</a> <span class="p1">(<span class="default"><font color="Maroon">z1</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">z2</font></span>)</span> <a href="xxreal_0.html#R1">&lt;</a>  <a href="sin_cos.html#K35">PI</a>  iff  <a href="comptrig.html#K1">Arg</a> <span class="p1">(<span class="default"><font color="Maroon">z2</font> <a href="xcmplx_0.html#K6">-</a> <font color="Maroon">z1</font></span>)</span> <a href="xxreal_0.html#NR2" target="_self">&gt;=</a>  <a href="sin_cos.html#K35">PI</a>  )
 ;<br/>


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