Three-Dimensional-Geometry Question 430
Question: If $ P(3,,4,,5), $ $ Q(4,,6,,3), $ $ R(-1,,2,,4), $ $ S(1,,0,,5) $ then the projection of RS on PQ is
[Orissa JEE 2002; RPET 2002]
Options:
A) ? 2/3
B) ? 4/3
C) ½
D) 2
Show Answer
Answer:
Correct Answer: B
Solution:
Here, $ x_2-{x_{\grave{\ }1}}=2,,y_2-y_1=-2,,z_2-z_1=1 $ Now, l, m, n for PQ are $ \frac{1}{3},\frac{2}{3},,\frac{-2}{3} $
$ \therefore $ Projection of RS on PQ = $ \sum l(x_2-x_1) $ = $ \frac{2}{3}-\frac{4}{3}-\frac{2}{3}=\frac{-4}{3} $ .
BETA
