Theorem: A line parallel to one side of a triangle divides the other two proportionately. In the figure below, segment DE is parallel to segment BC and segment EF is parallel to AB: In the figure below, segment DE is parallel to segment BC and segment EF is parallel to AB: The figure shows triangle ABC with segments DE and EF. Point D is on side AB, point E is on side AC, and point F is on side BC. Segment AD is 18, segment AE is 24, segment EC is 20, and segment FC is 30. Segment BF = 16 Segment BD = 20 Segment BD = 15 Segment BF = 32