Three Dimensional Geometry System Of Co Ordinates Direction Cosines And Direction Ratios Projection Question 58
Question: The direction cosines of the line joining the points (4, 3, ? 5) and (? 2, 1, ? 8) are [MP PET 2001]
Options:
A) $ ( \frac{6}{7},\frac{2}{7},\frac{3}{7} ) $
B) $ ( \frac{2}{7},\frac{3}{7},\frac{6}{7} ) $
C) $ ( \frac{6}{7},\frac{3}{7},\frac{2}{7} ) $
D) None of these
Answer:
Correct Answer: A
Solution:
D.c?s of line PQ is $ l=\frac{x_2-x_1}{|PQ|},,m=\frac{y_2-y_1}{|PQ|},,n=\frac{z_2-z_1}{|PQ|} $ $ \because $ $ x_2-x_1=-6,,y_2-y_1=-2,,z_2-z_1=-3 $ and $ |PQ|=\sqrt{36+4+9}=7 $ \ $ l=\frac{6}{7},,m=\frac{2}{7},,n=\frac{3}{7} $ .
BETA
