How can I get Tangential direction Vector in Python
<p>I can get some info from a Arc.</p>

<ul>
<li>FirstPoint ã [x,y,z]</li>
<li>LastPoint  ã [x,y,z]</li>
<li>Center ãã   [x,y,z]</li>
<li>Axis   ãã ã [x,y,z] # Perpendicular to the plane</li>
</ul>

<p>How can I get the FirstPoint&amp;LastPoint's tangential direction Vector ?</p>

<p>I want to get a intersection Point from two direction vector.</p>

<p>PS: Work in FreeCAD.</p>

<p>Thanks for any reply</p>

<p>best regards,
Eason</p>

<p>Circular arc from <code>A</code> to <code>B</code> with center <code>M</code> and normal vector <code>N</code>.</p>

<p>The tangent directions can be obtained by the <em>cross product</em>. </p>

<ul>
<li>Tangent at <code>A</code>: <code>N x (A-M)</code></li>
<li>Tangent at <code>B</code>: <code>(B-M) x N</code></li>
</ul>

<p>Both correspond to a rotation of 90DEG or -90DEG of the radius vectors around the axis <code>N</code></p>

python math direction freecad