Question 398231
<pre>
{{{drawing(19200/59,9600/59,-6,6,-1,5,

triangle(-5,0,5,0,0,5tan(40*pi/180)),
red(arc(-5,0,3,-3,0,40), arc(5,0,3,-3,140,180)),
locate(-3.3,.9,"40°"), locate(2.8,.9,"40°")




 )}}}

It is an isosceles triangle because the base angles
are congruent.  The two slanted sides are congruent.

Edwin</pre>