Quantitative Aptitude Ques 1454

Question: In $ \Delta ABC, $ X and Y are points on sides AB and BC, respectively such that $ XY||AC $ and XY divides triangular region ABC into two parts equal in area. Then, $ \frac{AX}{AB} $ is equal to

Options:

A) $ \frac{2+\sqrt{2}}{2} $

B) $ \frac{\sqrt{2}+3}{2} $

C) $ \frac{2-\sqrt{2}}{2} $

D) $ \frac{3-\sqrt{2}}{2} $

Show Answer

Answer:

Correct Answer: C

Solution:

  • According to the question,
    $ \frac{Areaof\Delta ABC}{Areaof\Delta BXY}=\frac{2}{1} $

$ \Rightarrow $ $ \frac{AB^{2}}{BX^{2}}=\frac{2}{1} $
$ \Rightarrow $ $ \frac{AB}{BX}=\frac{\sqrt{2}}{1} $ [ $ \because $ ratio of area of similar triangles $ ={{(ratiocorrespondingside)}^{2}} $ ] Subtracting 1 on both sides, we get $ \frac{AB}{BX}-1=\frac{\sqrt{2}}{1}-1 $

$ \Rightarrow $ $ \frac{AB-BX}{BX}=\frac{\sqrt{2}-1}{1} $

$ \therefore $ $ \frac{AX}{BX}=\frac{\sqrt{2}-1}{1} $
$ \Rightarrow $ $ \frac{BX}{AX}=\frac{1}{\sqrt{2}-1} $ [reciprocal] On adding 1 in both sides, we get $ \frac{BX}{AX}+1=\frac{1}{\sqrt{2}-1}+1 $

$ \Rightarrow $ $ \frac{BX+AX}{AX}=\frac{\sqrt{2}}{\sqrt{2}-1} $
$ \Rightarrow $ $ \frac{AB}{AX}=\frac{\sqrt{2}}{\sqrt{2}-1} $

$ \Rightarrow $ $ \frac{AX}{AB}=\frac{\sqrt{2}-1}{\sqrt{2}} $ [reciprocal]

$ \Rightarrow $ $ \frac{AX}{AB}=\frac{\sqrt{2}-1}{\sqrt{2}}\times \frac{\sqrt{2}}{\sqrt{2}} $
$ \Rightarrow $ $ \frac{AX}{AB}=\frac{2-\sqrt{2}}{2} $