Question drawn from very renowned book RD sharma of class 10th, Chapter no. 4
Chapter name:- Triangles
Exercise :- 4.2
This is very important question of triangle.
In this question we have ΔABC,
And D and E are points on the sides AB and AC respectively such that DE || BC.
Also it is given that AD = x cm, DB = x – 2 cm, AE = x + 2 cm, and EC = x – 1 cm,
Now we have to find the value of x
learning CBSE maths in efficient way
RD sharma, DHANPAT RAI publication
Class 10th, triangle
Given:
Length of side AD = x, DB = x – 2, AE = x + 2 and EC = x – 1
To find: Value of x.
By using Thales Theorem, we get
AD/BD = AE/CE – equation 1
Now, putting values in equation 1,
x/(x – 2) = (x + 2)/(x – 1)
x(x – 1) = (x – 2)(x + 2)
x 2– x – x2 + 4 = 0
∴ x = 4
Therefore, the value of x is 4