Question 537562
<pre>
{{{drawing(400,400,-2,2,-2,2, arc(-.1,0,2.2,-2.2,0,180),
arc(0,0,2.4,-2.4,180,360), arc(-.1,0,2.6,-2.6,0,86)


,grid(1) )}}} 

450° has reference angle of 90°.  The secant is 1 over the
cosine.  The cosine of 90° is 0, and 1 over zero is undefines,
so sec(450°) is undefined.

Edwin</pre>