Question taken from RD sharma

Class 10th

Chapter no. 4

Chapter name:- Triangles

Exercise :- 4.3

This is very basic and important questions.

In this question we have been given a ∆ABC,in which AD is the bisector of ∠A, meeting side BC at D.

Also we have that BD = 2.5 cm, AB = 5 cm and AC = 4.2 cm,

Now we have to find DC

Understanding and learning CBSE maths

RD sharma, DHANPAT RAI publication

Given: Δ ABC and AD bisects ∠A, meeting side BC at D. And AB = 3.5 cm, AC = 4.2 cm, and DC = 2.8 cm.

Required to find: BD

Since, AD is the bisector of ∠ A meeting side BC at D in Δ ABC

⇒ AB/ AC = BD/ DC

3.5/ 4.2 = BD/ 2.8

4.2 x BD = 3.5 x 2.8

BD = 7/3

∴ BD = 2.3 cm