ABC IS A TRIANGLE AND AD AND BE ARE ITS MEDIANS AND DF II BE.SHOW THAT BC =4CF.

wen u draw the diagram u can understand properly.

using the similar triangles principle in the triangle CEB, using the condition that BE II DF 

we get EC=2CF , DC=2CF 

then since BE, AD ARE the medians to AC,BC

AC=2CE , BC=2CD

sustituting this in the above condition we get

AC=4CF, Ans.BC=4CF