Question

In triangle ABC, If DE parallel to BC and ratio of sides ADand DB IS 2:4 find the ratio of DE:BC

Answer 1

in triangle ABC
DE is parallel to BC so
 AC is a transversal 
angle ADE=angle ABC (corresponding angles)
angle AED=angle ACB(corresponding angles)
triangle AED ~ triangle ABC by AA similarity rule
AD:AB=AE:AC=DE:BC=2:4/1:2