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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="diraf.html#NM1">AffinSpace</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font> be   <a href="struct_0.html#NM1">Element</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> be   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>







<b>assume </b><b>that </b><br/><a NAME="E1:56"/><i><font color="Green">E46</font></i>: 
( <font color="Maroon">c<sub>3</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a>  &amp; <font color="Maroon">c<sub>4</sub></font> <a href="aff_4.html#NR1" target="_self">is_plane</a>  )
 <b>and </b><br/><a NAME="E2:56"/><i><font color="Green">E47</font></i>: 
( <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>3</sub></font> &amp; <font color="Maroon">c<sub>2</sub></font> <a href="hidden.html#R2">in</a> <font color="Maroon">c<sub>4</sub></font> )
 <b>and </b><br/><a NAME="E3:56"/><i><font color="Green">E48</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="aff_4.html#R1" target="_self">'||'</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<b>consider </b><font color="Maroon">c<sub>5</sub></font> being   <a href="struct_0.html#NM2">Subset</a> of <font color="Maroon">c<sub>1</sub></font><b> such that </b><br/><a NAME="E5:56"/><i><font color="Green">E49</font></i>: 
<font color="Maroon">c<sub>5</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>4</sub></font>
 <b>and </b><br/><a NAME="E6:56"/><i><font color="Green">E50</font></i>: 
( <font color="Maroon">c<sub>3</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>5</sub></font> or <font color="Maroon">c<sub>5</sub></font> <a href="aff_1.html#R4">//</a> <font color="Maroon">c<sub>3</sub></font> )
 <b>by </b><i><a class="txt" href="aff_4.html#E1:56"><i><font color="Green">E46</font></i></a>, <a class="txt" href="aff_4.html#E3:56"><i><font color="Green">E48</font></i></a>, <a class="ref" href="aff_4.html#T41" target="_self">Th41</a></i>;<br/>
<a NAME="E7:56"/><i><font color="Green">E51</font></i>: 
<font color="Maroon">c<sub>5</sub></font> <a href="aff_1.html#NR2" target="_self">is_line</a> 
 
<b>by </b><i><a class="txt" href="aff_4.html#E6:56"><i><font color="Green">E50</font></i></a>, <a class="ref" href="aff_1.html#T50">AFF_1:50</a></i>;<br/>
<font color="Maroon">c<sub>3</sub></font> = 
<font color="Maroon">c<sub>2</sub></font> <a href="aff_4.html#K2" target="_self">*</a> <font color="Maroon">c<sub>3</sub></font>
<b>by </b><i><a class="txt" href="aff_4.html#E1:56"><i><font color="Green">E46</font></i></a>, <a class="txt" href="aff_4.html#E2:56"><i><font color="Green">E47</font></i></a>, <a class="txt" href="aff_4.html#E42"><i><font color="Green">Lemma35</font></i></a></i>
<br/>.= 
<font color="Maroon">c<sub>2</sub></font> <a href="aff_4.html#K2" target="_self">*</a> <font color="Maroon">c<sub>5</sub></font>
<b>by </b><i><a class="txt" href="aff_4.html#E6:56"><i><font color="Green">E50</font></i></a>, <a class="ref" href="aff_4.html#T32" target="_self">Th32</a></i>
;<br/>
<b>hence </b><a NAME="E9:56"/>
<font color="Maroon">c<sub>3</sub></font> <a href="tarski.html#R1">c=</a> <font color="Maroon">c<sub>4</sub></font>
 <b>by </b><i><a class="txt" href="aff_4.html#E1:56"><i><font color="Green">E46</font></i></a>, <a class="txt" href="aff_4.html#E2:56"><i><font color="Green">E47</font></i></a>, <a class="txt" href="aff_4.html#E5:56"><i><font color="Green">E49</font></i></a>, <a class="txt" href="aff_4.html#E7:56"><i><font color="Green">E51</font></i></a>, <a class="ref" href="aff_4.html#T28" target="_self">Th28</a></i>;<br/>


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