In: Math
In triangle ABC, DE || BC. AD = x, DB = x - 2, AE = x + 2 and EC = x - 1, find the value x.
In △ABC, we have DE || BC
Therefore
From Thales theorem, we know that the ratio of any two corresponding sides in two equiangular triangles is always the same. This theorem is called as Basic Proportionality Theorem
AD /DB = AE/ EC
AD × EC = AE × DB
On substituting the known values we get
x(x-1) = (x-2)(x+2)
x2 – x = x2 – 4
-x=-4
x = 4
The value of x =4.