Question extracted from RD sharma of class 10th, Chapter no. 4
Chapter name:- Triangles
Exercise :- 4.2
This is very basic and important questions. And has been asked in several times in exams.
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 = 3/4 and AC = 15 cm,
Now we have to Find AE.
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RD sharma, DHANPAT RAI publication
Given:
Length of side AD/BD = 3/4 and AC = 15 cm
To find: Length of side AE
By using Thales Theorem, we get
AD/BD = AE/CE – equation 1
Let, AE = x
Then CE = 15 – x.
Now, putting values in equation 1,
⇒ 3/4 = x/ (15 – x)
45 – 3x = 4x
-3x – 4x = – 45
7x = 45
x = 45/7
x = 6.43 cm
∴ AE= 6.43cm
Therefore, Length of side AE is 6.43 cm