Question

Adrian is using an indirect method to prove that segment DE is not parallel to segment BC in the triangle ABC shown below:

Answer 1

If we start with the assumption that segment DE is parallel to segment BC, then we the similarity condition that:
triangle ABC is similar to triangle ADE
For this to be true, the ratio corresponding sides of the two triangles must be equal. So:
5/8 =? 6/10
But
5/8 =/= 6/10

So, DE is not parallel to BC