Aplicam teorema lui Thales
In orice triunghi, o paralela la o latura, imparte celelalte doua laturi in segmente proportionale.
[tex] \frac{AD}{BD} = \frac{AE}{EC} => \frac{2}{5} = \frac{AE}{10}=>AE*5=2*10=>AE= \frac{2*10}{5}=4 cm [/tex]
[tex]AB=AD+DB=2+5=7cm[/tex]