Given triangle ABC with points Eand F on sides AB and AC respectively in such a way that EF is parallel to BC.
Triangle AEF is similar to Triangle ABC because the corresponding angles are equal.(A is common and the other pairs are corresponding parts of parallel lines)
Then you have the sides in proportion because they are corresponding parts of similar triangles.
You should be able to write that up is so-called 2 column form!

Paul M.
01/23/19
Jim S.
Thanks so much!01/24/19
Jim S.
can you please give me the statements for what you are saying?01/23/19