Question

Solve for AD http://www.usatestprep.com/modules/gallery/files/15/1558/1558.gif

Answer 1

Triangles ADF and EGF are similar. So the ratio of lengths of corresponding sides are equal.
\[\frac{ AF }{ EF }=\frac{ AD }{ EG }\]
\[\frac{ AE+EF }{ EF }=\frac{ AD }{ EG }\]
\[\frac{ 6+6 }{ 6}=\frac{ AD }{ 4}\]
\[\frac{ 12 }{ 6}=\frac{ AD }{ 4 }\]
\[2=\frac{ AD }{ 4 }\]
Does that help? @rolandito97