Pair Of Straight Lines Question 120
Question: The angle between the pair of straight lines $ y^{2}{{\sin }^{2}}\theta -xy{{\sin }^{2}}\theta +x^{2}({{\cos }^{2}}\theta -1)=1, $ is
[MNR 1985; UPSEAT 2000; Kerala (Engg.) 2005]
Options:
A) $ \frac{\pi }{3} $
B) $ \frac{\pi }{4} $
C) $ \frac{2\pi }{3} $
D) None of these
Show Answer
Answer:
Correct Answer: D
Solution:
$ \alpha ={{\tan }^{-1}}{ \frac{2\sqrt{\frac{{{\sin }^{2}}\theta }{4}-{{\sin }^{2}}\theta ({{\cos }^{2}}\theta -1)}}{{{\sin }^{2}}\theta +{{\cos }^{2}}\theta -1} } $
$ ={{\tan }^{-1}}\infty \Rightarrow \alpha =\frac{\pi }{2} $
BETA
