Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Geometry

Question:

In $\triangle A B C, D$ and $E$ are points on sides $A B$ and $A C$, such that $D E$ II $B C$. If $A D=x+3, D B$ $=2 x-3, A E=x+1$ and $E C=2 x-2$, then the value of $x$ is:

Options:

$\frac{4}{5}$

$ \frac{1}{2}$

$ \frac{3}{5}$

$ \frac{1}{5}$

Correct Answer:

$ \frac{3}{5}$

Explanation:

Concept Used

When two triangles are similar, their corresponding angles are equal and their corresponding sides are proportional.

Calculation

As DE is parallel to BC and \(\angle\)A is common in both \(\Delta \) ABC and \(\Delta \)ADE

So, ABC is similar to ADE

So,

\(\frac{AB}{AD}\) = \(\frac{AC}{AE}\)

= \(\frac{x\;+\;3\;+\;2x\;-\;3}{x\;+\;3}\) = \(\frac{x\;+\;1\;2x\;-\;2}{x\;+\;1}\)

= \(\frac{3x}{x\;+\;3}\) = \(\frac{3x\;-\;1}{x\;+\;1}\)

= \( { 3x}^{2 } \) + 3x = \( { 3x}^{2 } \) - x + 9x - 3

= 3x = 8x - 3

= 5x = 3

= x = \(\frac{3}{5}\)

Therefore, x is \(\frac{3}{5}\)