Math
posted by James on .
If ∆ ABC ~ ∆ DEF, BC = 12 cm, EF = 10 cm, and AC = 18 cm, find DF.

The triangles are similar (but not congruent).
That means that corresponding sides are all in the same ratio.
BC/EF = 12/10 = AC/DF = 18/DF
DF = 18*(5/6) = 15 
by ratios
DF/10 = 18/12
solve for DF 
Please do not repost the same question without checking if your last post has been answered.
It causes unnecessary work by the tutors
http://www.jiskha.com/display.cgi?id=1294796964