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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="nat_1.html#NM1">Nat</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font> be    <a href="subset_1.html#M2">Element</a> of  <a href="euclidlp.html#K1" target="_self">line_of_REAL</a> <font color="Maroon">c<sub>1</sub></font>;<br/>





<b>assume </b><a NAME="E1:120"/><i><font color="Green">E98</font></i>: 
( <font color="Maroon">c<sub>2</sub></font> <a href="euclidlp.html#R5" target="_self">//</a> <font color="Maroon">c<sub>3</sub></font> &amp; <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>3</sub></font> )
 ;<br/>

<a NAME="E2:120"/><b>then </b><i><font color="Green">E99</font></i>: 
<font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>3</sub></font> <a href="euclidlp.html#R7" target="_self">are_coplane</a> 
 
<b>by </b><i><a class="ref" href="euclidlp.html#T102" target="_self">Th102</a></i>;<br/>
<a NAME="E3:120"/><i><font color="Green">E100</font></i>: 
<font color="Maroon">c<sub>2</sub></font> <a href="xboole_0.html#R1">misses</a> <font color="Maroon">c<sub>3</sub></font>
 
<b>by </b><i><a class="txt" href="euclidlp.html#E1:120"><i><font color="Green">E98</font></i></a>, <a class="ref" href="euclidlp.html#T76" target="_self">Th76</a></i>;<br/>
<a NAME="E4:120"/>
( <font color="Maroon">c<sub>2</sub></font> <a href="euclid_4.html#NR1" target="_self">is_line</a>  &amp; <font color="Maroon">c<sub>3</sub></font> <a href="euclid_4.html#NR1" target="_self">is_line</a>  )
 
<b>by </b><i><a class="txt" href="euclidlp.html#E1:120"><i><font color="Green">E98</font></i></a>, <a class="ref" href="euclidlp.html#T71" target="_self">Th71</a></i>;<br/>
<b>hence </b><a NAME="E5:120"/>
ex <font color="Olive">b<sub>1</sub></font> being   <a href="subset_1.html#M2">Element</a> of  <a href="euclidlp.html#K5" target="_self">plane_of_REAL</a> <font color="Maroon">c<sub>1</sub></font> st <br/>( <font color="Maroon">c<sub>2</sub></font> <a href="tarski.html#R1">c=</a> <font color="Olive">b<sub>1</sub></font> &amp; <font color="Maroon">c<sub>3</sub></font> <a href="tarski.html#R1">c=</a> <font color="Olive">b<sub>1</sub></font> &amp; <font color="Olive">b<sub>1</sub></font> is <a href="euclidlp.html#V1" target="_self">being_plane</a> )
 <b>by </b><i><a class="txt" href="euclidlp.html#E2:120"><i><font color="Green">E99</font></i></a>, <a class="txt" href="euclidlp.html#E3:120"><i><font color="Green">E100</font></i></a>, <a class="ref" href="euclidlp.html#T103" target="_self">Th103</a></i>;<br/>


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