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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> be   <a href="vectsp_1.html#NM2">Field</a>;<br/><b>let </b><font color="Maroon">c<sub>3</sub></font> be   <a href="matrix_1.html#NM5">Matrix</a> of <font color="Maroon">c<sub>1</sub></font>,<font color="Maroon">c<sub>2</sub></font>;<br/>





<b>assume </b><a NAME="E1:34"/>
( <font color="Maroon">c<sub>3</sub></font> is <a href="matrix_8.html#V4" target="_self">Self_Reversible</a> &amp; <font color="Maroon">c<sub>3</sub></font> is <a href="matrix_6.html#V2">symmetrical</a> )
 ;<br/>

<a NAME="E2:34"/><b>then </b>
( <font color="Maroon">c<sub>3</sub></font> is <a href="matrix_6.html#V1">Reversible</a> &amp; <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>3</sub></font> <a href="matrix_6.html#K5">~</a>  &amp; <font color="Maroon">c<sub>3</sub></font> <a href="hidden.html#R1">=</a> <font color="Maroon">c<sub>3</sub></font> <a href="matrix_1.html#K5">@</a>  )
 
<b>by </b><i><a class="ref" href="matrix_6.html#D5">MATRIX_6:def 5</a>, <a class="ref" href="matrix_8.html#D4" target="_self">Def4</a></i>;<br/>
<b>hence </b><a NAME="E3:34"/>
<font color="Maroon">c<sub>3</sub></font> is <a href="matrix_6.html#V4">Orthogonal</a>
 <b>by </b><i><a class="ref" href="matrix_6.html#D7">MATRIX_6:def 7</a></i>;<br/>


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