Three Dimensional Geometry Question 84
Question: A line makes angles $ \alpha ,\beta ,\gamma $ with the co-ordinate axes. If $ \alpha +\beta =90^{o} $ , then $ \gamma = $
Options:
A) 0
B) $ 90{}^\circ $
C) $ 180{}^\circ $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
Here, $ {{\cos }^{2}}\alpha +{{\cos }^{2}}(90-\alpha )+{{\cos }^{2}}\gamma =1 $
Þ $ {{\cos }^{2}}\alpha +{{\sin }^{2}}\alpha +{{\cos }^{2}}\gamma =1 $
Þ $ {{\cos }^{2}}\gamma +1=1\Rightarrow \gamma =90^{o} $ .
BETA
