"Easy" triangle problem (hight school)

Question

Can someone give me a hint to this "easy" problem? In the triangle ABC, we have: DE || BC, FE||DC, AF=1, FD=2, find DB=?

Roman83 · Accepted Answer · 2016-07-14T10:51:18.060

4

1) $$FE||DC \Rightarrow\frac{AF}{FD}=\frac{AE}{EC}=\frac{1}{2}$$ 2) $$\frac{AD}{DB}=\frac{AE}{EC}=\frac{1}{2}$$ Hence, $BD=2AD=6$

edited Jul 14 '16 at 10:51

answered Jul 14 '16 at 10:40

Roman83

1

@5xum: I edited – Roman83 Jul 14 '16 at 10:44
Thank you very much! B.t.w. does this first rule have a special name?! – Maxtron Moon Jul 14 '16 at 10:47
2

Thales' theorem – Roman83 Jul 14 '16 at 10:51

1 Answers1