Vector Algebra Question 263
Question: The position vectors of P and Q are $ 5\mathbf{i}+4\mathbf{j}+a\mathbf{k} $ and $ -\mathbf{i}+2\mathbf{j}-2\mathbf{k} $ respectively. If the distance between them is 7, then the value of a will be
Options:
A) 5, 1
B) 5, 1
C) 0, 5
D) 1, 0
Show Answer
Answer:
Correct Answer: A
Solution:
- $ 7=\sqrt{{{(5+1)}^{2}}+{{(4-2)}^{2}}+{{(a+2)}^{2}}}\Rightarrow a+2=\pm 3 $ or $ a,=-5,1. $
BETA
