Three Dimensional Geometry Question 70
Question: If the length of a vector be 21 and direction ratios be 2, - 3, 6 then its direction cosines are
Options:
A) $ \frac{2}{21},\frac{-1}{7},\frac{2}{7} $
B) $ \frac{2}{7},\frac{-3}{7},\frac{6}{7} $
C) $ \frac{2}{7},\frac{3}{7},\frac{6}{7} $
D) None of these
Show Answer
Answer:
Correct Answer: B
Solution:
D.c.’s are $ \frac{2}{\sqrt{2^{2}+{{(-3)}^{2}}+6^{2}}},\frac{-3}{\sqrt{49}}and,\frac{6}{\sqrt{49}} $ or $ \frac{2}{7},,\frac{-3}{7},\frac{6}{7} $ .
BETA
