2013 AMC 12A Problems/Problem 9
Revision as of 21:56, 6 February 2013 by Epicwisdom (talk | contribs) (Created page with "Note that because <math>\bar{DE}</math> and <math>\bar{EF}</math> are parallel to the sides of <math>\triangle ABC</math>, the internal triangles <math>\triangle BDE</math> and <...")
Note that because 
and 
are parallel to the sides of 
, the internal triangles 
and 
are similar to , and are therefore also isosceles triangles.
It follows that 
. Thus, 
.
Since opposite sides of parallelograms are equal, the perimeter is 
.
