Three-Dimensional-Geometry Question 440
Question: The co-ordinates of points $ A,B,C,D $ are (a, 2, 1), (1, ?1, 1), (2, ? 3, 4) and (a+1, a+2, a+3) respectively. If $ AB=5 $ and $ CD=6 $ , then $ a= $
Options:
A) 2
B) 3
C) ? 2
D) ? 3
Show Answer
Answer:
Correct Answer: D
Solution:
$ AB=\sqrt{{{(a-1)}^{2}}+3^{2}+0}=5 $
$ \Rightarrow a-1=\pm ,4 $
$ \Rightarrow a=-3,5 $ $ CD=\sqrt{{{(a-1)}^{2}}+{{(a+5)}^{2}}+{{(a-1)}^{2}}}=6 $
$ \Rightarrow a^{2}-2a-15=0\Rightarrow a=-3,5 $ But common solution of (i) and (ii) is ? 3.
BETA
