Three Dimensional Geometry Question 279
Question: If $ A,B,C,D $ are the points (2, 3, ?1),(3, 5, ?3), (1, 2, 3), (3, 5, 7) respectively, then the angle between AB and CD is
[Orissa JEE 2003]
Options:
A) $ \frac{\pi }{2} $
B) $ \frac{\pi }{3} $
C) $ \frac{\pi }{4} $
D) $ \frac{\pi }{6} $
Show Answer
Answer:
Correct Answer: A
Solution:
D.r?s of AB º $ (1,,2,,-2) $ , D.r?s of $ CD\equiv (2,,3,,4) $ \ $ a_1a_2+b_1b_2+c_1c_2=0 $ ; \ $ \cos \theta =0 $
Þ $ \theta =\pi /2 $ .
BETA
