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<b>let </b><font color="Maroon">p1</font> be   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 3</span>)</span>;<br/><b>let </b><font color="Maroon">p2</font> be   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 3</span>)</span>;<br/><b>let </b><font color="Maroon">p3</font> be   <a href="pre_topc.html#NM2">Point</a> of <span class="p1">(<span class="default"><a href="euclid.html#K15">TOP-REAL</a> 3</span>)</span>;<br/>





<span class="p1">(<span class="default"><font color="Maroon">p1</font> <a href="euclid.html#K17">+</a> <font color="Maroon">p2</font></span>)</span> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font> = 
 <a href="euclid.html#K19">-</a> <span class="p1">(<span class="default"><font color="Maroon">p3</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <span class="p2">(<span class="default"><font color="Maroon">p1</font> <a href="euclid.html#K17">+</a> <font color="Maroon">p2</font></span>)</span></span>)</span>
<b>by </b><i/>
<br/>.= 
 <a href="euclid.html#K19">-</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">p3</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p1</font></span>)</span> <a href="euclid.html#K17">+</a> <span class="p2">(<span class="default"><font color="Maroon">p3</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p2</font></span>)</span></span>)</span>
<b>by </b><i/>
<br/>.= 
 <a href="euclid.html#K19">-</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">p3</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p1</font></span>)</span> <a href="euclid.html#K17">+</a> <span class="p2">(<span class="default"><a href="euclid.html#K19">-</a> <span class="p3">(<span class="default"><font color="Maroon">p2</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font></span>)</span></span>)</span></span>)</span>
<b>by </b><i/>
<br/>.= 
 <a href="euclid.html#K19">-</a> <span class="p1">(<span class="default"><span class="p2">(<span class="default"><font color="Maroon">p3</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p1</font></span>)</span> <a href="euclid.html#K20">-</a> <span class="p2">(<span class="default"><font color="Maroon">p2</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font></span>)</span></span>)</span>
<b>by </b><i><a class="ref" href="euclid.html#T45">EUCLID:45</a></i>
<br/>.= 
<span class="p1">(<span class="default"><a href="euclid.html#K19">-</a> <span class="p2">(<span class="default"><font color="Maroon">p3</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p1</font></span>)</span></span>)</span> <a href="euclid.html#K17">+</a> <span class="p1">(<span class="default"><font color="Maroon">p2</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font></span>)</span>
<b>by </b><i><a class="ref" href="euclid.html#T48">EUCLID:48</a></i>
;<br/>
<b>hence </b><a NAME="E2:26"/>
<span class="p1">(<span class="default"><font color="Maroon">p1</font> <a href="euclid.html#K17">+</a> <font color="Maroon">p2</font></span>)</span> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font> <a href="hidden.html#R1">=</a> <span class="p1">(<span class="default"><font color="Maroon">p1</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font></span>)</span> <a href="euclid.html#K17">+</a> <span class="p1">(<span class="default"><font color="Maroon">p2</font> <a href="euclid_5.html#K5" target="_self">&lt;X&gt;</a> <font color="Maroon">p3</font></span>)</span>
 <b>by </b><i/>;<br/>


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