Question

A triangle ABC AB =5 cm and BC =8 cm and CA=7 cm if D and e are respectively of midpoint of Ab and BC find the length of the DE.

Answer 1

By Mid Point theorem, Line joining the mid points of two sides of triangle is parallel to the third side and equal to half of it.
So, 

Answer 2

answer is √db×db+be×be=de
which comes to be 4.71