The sine of the angle between the pair of lines represented by the equation \(x^2-7 x y+12 y^2=0\) is
The sine of the angle between the pair of lines represented by the equation \(x^2-7 x y+12 y^2=0\) is
- \(\frac{1}{12}\)
- \(\frac{1}{13}\)
- \(\frac{1}{\sqrt{170}}\)
- \(\frac{1}{11}\)
Solution
\(\begin{aligned}
& x^2-7 x y+12 y^2 =0 \\
a & =1(2 h=-7) b=12 \\
\tan \theta & =\left|\frac{2 \sqrt{h^2-a b}}{a+b}\right| \\
& =\left|\frac{2 \sqrt{\frac{49}{4}-1 \cdot 12}}{13}\right|=\left|\frac{2 \cdot \frac{1}{2}}{13}\right|
\end{aligned}\)
\(\tan \theta=\frac{1}{13}\)

\(\sin \theta=\frac{1}{\sqrt{170}}\)
Hence, option (c) is correct.
Asked in: AP EAMCET 2020 (18 Sep Shift 2)
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