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MHT CET · Maths · Straight Lines

Two sides of a square are along the lines \(5 x-12 y+39=0\) and \(5 x-12 y+78=0\), then area of the square is

  1. A 9 sq. units.
  2. B \(\frac{1}{3}\) sq. units.
  3. C 18 sq. units.
  4. D 3 sq. units.
Verified Solution

Answer & Solution

Correct Answer

(A) 9 sq. units.

Step-by-step Solution

Detailed explanation

Given equations of lines are \(5 x-12 y+39=0\) and \(5 x-12 y+78=0\).
Slope of \(5 x-12 y+39=0\) is \(\frac{5}{12}\)
Slope of \(5 x-12 y+78=0\) is \(\frac{5}{12}\)
\(\therefore \quad\) Lines are parallel.
\(\therefore \quad\) Distance between two parallel lines \(=\left|\frac{\mathrm{c}_1-\mathrm{c}_2}{\sqrt{\mathrm{a}^2+\mathrm{b}^2}}\right|\)
\(\begin{aligned}
& =\left|\frac{39-78}{\sqrt{5^2+(-12)^2}}\right| \\
& =3 \text { units }
\end{aligned}\)
\(\therefore \quad\) Side of the square \(=3\) units
\(\therefore \quad\) Area of square \(=3^2=9\) sq. units