Question taken from RD sharma
Chapter no. 4
Chapter name:- Triangles
Exercise :- 4.2
This is very basic and important questions.
In this question we have a triangle ΔABC,
In which D and E are points on the sides AB and AC respectively such that DE || BC.
Also it is given that AD/DB = 2/3 and AC = 18 cm,
Now we have to find the length of AE.
Understanding and learning CBSE maths
RD sharma, DHANPAT RAI publication
Length of side AD/BD = 2/3 and AC = 18 cm
To find: Length of side AE.
By using Thales Theorem, we get
AD/BD = AE/CE – equation 1
Let, AE = x
Then CE = 18 – x
Now, putting values in equation 1,
⇒ 23 = x/ (18 – x)
3x = 36 – 2x
5x = 36 cm
x = 36/5 cm
x = 7.2 cm
∴ AE = 7.2 cm
Therefore, Length of side AE is 7.2 cm