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<b>let </b><font color="Maroon">c<sub>1</sub></font> be   <a href="incsp_1.html#NM4">IncSpace</a>;<br/><b>let </b><font color="Maroon">c<sub>2</sub></font>, <font color="Maroon">c<sub>3</sub></font>, <font color="Maroon">c<sub>4</sub></font> be   <a href="incsp_1.html#NM1">POINT</a> of <font color="Maroon">c<sub>1</sub></font>;<br/><b>let </b><font color="Maroon">c<sub>5</sub></font> be   <a href="incsp_1.html#NM2">LINE</a> of <font color="Maroon">c<sub>1</sub></font>;<br/>









<b>assume </b><b>that </b><br/><a NAME="E1:61"/><i><font color="Green">E39</font></i>: 
not <font color="Maroon">c<sub>2</sub></font> <a href="incsp_1.html#R1" target="_self">on</a> <font color="Maroon">c<sub>5</sub></font>
 <b>and </b><br/><a NAME="E2:61"/><i><font color="Green">E40</font></i>: 
<span class="p1"><a href="domain_1.html#K7">{</a><span class="default"><font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font></span><a href="domain_1.html#K7">}</a></span> <a href="incsp_1.html#R4" target="_self">on</a> <font color="Maroon">c<sub>5</sub></font>
 <b>and </b><br/><a NAME="E3:61"/><i><font color="Green">E41</font></i>: 
<font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#NR2" target="_self">&lt;&gt;</a> <font color="Maroon">c<sub>4</sub></font>
 ;<br/>

<b>set </b><font color="Maroon">c<sub>6</sub></font> =  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font>;<br/>
<a NAME="E4:61"/>
( <font color="Maroon">c<sub>2</sub></font> <a href="incsp_1.html#R2" target="_self">on</a>  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font> &amp; <font color="Maroon">c<sub>5</sub></font> <a href="incsp_1.html#R3" target="_self">on</a>  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font> )
 
<b>by </b><i><a class="txt" href="incsp_1.html#E1:61"><i><font color="Green">E39</font></i></a>, <a class="ref" href="incsp_1.html#D11" target="_self">Def11</a></i>;<br/>
<a NAME="E5:61"/><b>then </b>
( <font color="Maroon">c<sub>2</sub></font> <a href="incsp_1.html#R2" target="_self">on</a>  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font> &amp; <span class="p1"><a href="domain_1.html#K7">{</a><span class="default"><font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font></span><a href="domain_1.html#K7">}</a></span> <a href="incsp_1.html#R5" target="_self">on</a>  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font> )
 
<b>by </b><i><a class="txt" href="incsp_1.html#E2:61"><i><font color="Green">E40</font></i></a>, <a class="ref" href="incsp_1.html#T35" target="_self">Th35</a></i>;<br/>
<a NAME="E6:61"/><b>then </b>
<span class="p1"><a href="domain_1.html#K7">{</a><span class="default"><font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font></span><a href="domain_1.html#K7">}</a></span> <a href="subset_1.html#K4">\/</a> <span class="p1"><a href="domain_1.html#K6">{</a><span class="default"><font color="Maroon">c<sub>2</sub></font></span><a href="domain_1.html#K6">}</a></span> <a href="incsp_1.html#R5" target="_self">on</a>  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font>
 
<b>by </b><i><a class="ref" href="incsp_1.html#T19" target="_self">Th19</a></i>;<br/>
<a NAME="E7:61"/><b>then </b><i><font color="Green">E42</font></i>: 
<span class="p1"><a href="domain_1.html#K8">{</a><span class="default"><font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>2</sub></font></span><a href="domain_1.html#K8">}</a></span> <a href="incsp_1.html#R5" target="_self">on</a>  <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font>
 
<b>by </b><i><a class="ref" href="enumset1.html#T43">ENUMSET1:43</a></i>;<br/>
<a NAME="E8:61"/>
not <span class="p1"><a href="domain_1.html#K8">{</a><span class="default"><font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>2</sub></font></span><a href="domain_1.html#K8">}</a></span> <a href="incsp_1.html#NR6" target="_self">is_collinear</a> 
 
<b>by </b><i><a class="txt" href="incsp_1.html#E1:61"><i><font color="Green">E39</font></i></a>, <a class="txt" href="incsp_1.html#E2:61"><i><font color="Green">E40</font></i></a>, <a class="txt" href="incsp_1.html#E3:61"><i><font color="Green">E41</font></i></a>, <a class="ref" href="incsp_1.html#T39" target="_self">Th39</a></i>;<br/>
<b>hence </b><a NAME="E9:61"/>
 <a href="incsp_1.html#K3" target="_self">Plane</a> <font color="Maroon">c<sub>2</sub></font>,<font color="Maroon">c<sub>5</sub></font> <a href="hidden.html#R1">=</a>  <a href="incsp_1.html#K2" target="_self">Plane</a> <font color="Maroon">c<sub>3</sub></font>,<font color="Maroon">c<sub>4</sub></font>,<font color="Maroon">c<sub>2</sub></font>
 <b>by </b><i><a class="txt" href="incsp_1.html#E7:61"><i><font color="Green">E42</font></i></a>, <a class="ref" href="incsp_1.html#D10" target="_self">Def10</a></i>;<br/>


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