Three Dimensional Geometry Question 145
Question: A line which makes angle $ 60^{o} $ with y-axis and z-axis, then the angle which it makes with x-axis is
[RPET 2002; AMU 2005]
Options:
A) $ 45{}^\circ $
B) $ 60{}^\circ $
C) $ 75{}^\circ $
D) $ 30{}^\circ $
Show Answer
Answer:
Correct Answer: A
Solution:
$ {{\cos }^{2}}\alpha =1-{{\cos }^{2}}60^{\circ}-{{\cos }^{2}}60^{\circ} $ $ =1-\frac{1}{4}-\frac{1}{4}=\frac{1}{2} $ Þ $ \alpha =45^{o}. $
BETA
