AD¯¯¯¯¯, BD¯¯¯¯¯, and CD¯¯¯¯¯ are angle bisectors of the vertex angles of △ABC. AG=5 meters and AD=13 meters. What is DF?

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m
Triangle A B C with three dashed rays drawn that intersect at point D. Ray C D intersects side A B. Ray B D intersects side A C. Ray A D intersects side B C. Three line segments extend from point D. Segment DE is perpendicular to side A B. Segment F D is perpendicular to side B C. Segment G D is perpendicular to side A C.