Question

1. In a ABC, AD is the bisector of ZA, intersecting
the side BC at D.
() IF AB=5 cm, AC = 4.2 cm and DC =2.1 cm, find
BD​

Answer 1

Answer:

Given in △ABC, AD is the bisector of angle A

By internal angle bisector theorem, the bisector of vertical angle of a triangle divides the base in the ratio of the other two sides.

(i)  ACAB=DCBD

∴  4.25=DC2.5

∴  DC=52.5×4.2

∴  DC=2.1cm