Three-Dimensional-Geometry Question 435
Question: If $ ( \frac{1}{2},\frac{1}{3},n ) $ are the direction cosines of a line, then the value of n is
[Kerala (Engg.) 2002]
Options:
A) $ \frac{\sqrt{23}}{6} $
B) $ \frac{23}{6} $
C) $ \frac{2}{3} $
D) $ \frac{3}{2} $
Show Answer
Answer:
Correct Answer: A
Solution:
If $ ( \frac{1}{2},,\frac{1}{3},,n ) $ are the d.c?s of line then, $ {{( \frac{1}{2} )}^{2}}+{{( \frac{1}{3} )}^{2}}+n^{2}=1 $
Þ $ n^{2}=\frac{23}{36} $
Þ $ n=\frac{\sqrt{23}}{6} $ .
BETA
