Question

In a ΔABC, if DE∥BC, prove that AB/AD=AC/AE.

Answer 1

Solution:

Basic proportionality theorem states that if DE || BC, the point D divides AB, is the same as the ratio point E divides AC.

The ratio in which point D divides AB is given by AD/DB.

Similarly, point E divides AC as AE/EC

That is AD/DB = AE/EC

Or we can write as DB/AD = EC/AE

On adding ‘1’ on both sides, we get

AB/AD = AC/AE

Hence proved.