Question

see the question no. 25

can you explain me why we have to take AD/AB = DE/BC to find the value of DE ,

I think we should take AD/BC = DE/AB

Answer 1

We take AD/DC=AE/EB

and DE parallel to BC because of Basic Proportionality Theorem,

In this theorem's , we can read this

If a line is drawn one parallel side of a triangle intersect other two side at distinct points, then other two sides are divided into same ratio.

HOPE IT CLEARS YOUR DOUBT,

THANKS!!!!