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Question: Answered & Verified by Expert
The sine of the angle between the pair of lines represented by the equation \(x^2-7 x y+12 y^2=0\) is
MathematicsPair of LinesAP EAMCETAP EAMCET 2020 (18 Sep Shift 2)
Options:
  • A \(\frac{1}{12}\)
  • B \(\frac{1}{13}\)
  • C \(\frac{1}{\sqrt{170}}\)
  • D \(\frac{1}{11}\)
Solution:
2403 Upvotes Verified Answer
The correct answer is: \(\frac{1}{\sqrt{170}}\)
\(\begin{aligned}
& x^2-7 x y+12 y^2 =0 \\
a & =1(2 h=-7) b=12 \\
\tan \theta & =\left|\frac{2 \sqrt{h^2-a b}}{a+b}\right| \\
& =\left|\frac{2 \sqrt{\frac{49}{4}-1 \cdot 12}}{13}\right|=\left|\frac{2 \cdot \frac{1}{2}}{13}\right|
\end{aligned}\)
\(\tan \theta=\frac{1}{13}\)


\(\sin \theta=\frac{1}{\sqrt{170}}\)
Hence, option (c) is correct.

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