Question drawn from very renowned book RD sharma of class 10th, Chapter no. 4

Chapter name:- Triangles

Exercise :- 4.3

This is very important question based on triangle fundamental properties.

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

Also the sides measurements are given AC = 4.2 cm, DC = 6 cm and BC = 10 cm,

Now we have to find AB

learning CBSE maths in efficient way

RD sharma, DHANPAT RAI publication

Class 10th, triangle

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

⇒ AB/ AC = BD/ DC

AB/ 4.2 = BD/ 6

We know that,

BD = BC – DC = 10 – 6 = 4 cm

⇒ AB/ 4.2 = 4/ 6

AB = (2 x 4.2)/ 3

∴ AB = 2.8 cm