Question

In the given figure, if DE/BC=2/3 and AE=10cm, then AB is_______
a) 16cm b) 12cm c) 15cm d) 18cm

http://assets.openstudy.com/updates/attachments/50efa311e4b0d4a537ce1e4e-singhmmm-1357882150386-download.png

Answer 1

triangle ADE is similar with triangle ABC (angle-angle-angle)
the proportion all sides will same, is 2/3
so, AE/AB = 2/3 or
10/AB = 2/3
solve for AB

Answer 2

@RadEn That's a waste of time when you already proved that two angles are common with each other. You don't go proving that the third angle is similar.

Answer 3

third angle is the same*