Question 480352
{{{drawing(400,300,-2,2,-1,2,
locate(-1,0,B),locate(0,0,D), locate(1,0,C), locate(0,1.7,A),
rectangle(-.1,0,0,.1), arc(0,1.5,.5,-.5,236.3099,270), 
arc(0,1.5,.6,-.6,270,303.69),
triangle(-1,0,1,0,0,1.5), triangle(-1,0,0,0,0,1.5) )}}}
<pre>

&#8736;BAD &#8773; &#8736;CAD          |  given
  AD &#8773; AD             |  reflexive property of congruence
&#8736;BDA is a right angle |  AD &#10200; BC is given
&#8736;CDA is a right angle |  AD &#10200; BC is given
&#8736;BDA &#8773; &#8736;CDA          |  all right angles are congruent.
&#916;ADB &#8773; &#916;ADC           |  angle-side-angle
  AB &#8773; AC             |  corr. parts of congruent triangles
&#916;ABC is isosceles     |  &#916;ABC has two congruent sides 

Edwin</pre>