Question 1029335
<pre>
{{{tan(13pi/4)}}}

Change {{{13pi/4}}} to degrees:

{{{expr(13pi/4)*expr("180°"/pi)="585°"}}}

We subtract 360° enough times to get a
a positive coterminal angle less than 360°: 

585°-360° = 225° (it was only necessary to
subtract 360° one time.)

{{{tan(13pi/4)=sec("225°")}}}

That is in QIII, So to get the reference
angle, we subtract 180° from 225° and get 
225°-180° = 45°.

The tangent is + in QIII, so 

{{{tan(13pi/4)}}}{{{""=""}}}{{{""+tan("45°")}}}{{{""=""}}}{{{1}}}

Edwin</pre>