Question

The points A(4,5,1),B(0,-1,-1),C(3,9,4) and D(-4,4,4) are
[Kurukshetra CEE 2002]

• A. Collinear
• B. Coplanar
• C. Non- coplanar
• D. Non- Collinear and non-coplanar

Answer 1

The correct option is B

Coplanar

AB $\equiv$ (-4,-6,-2);AC $\equiv$ (-1,4,3);AD $\equiv$ (-8,-1,3)
Points A,B,C,D are coplaner, if [AB,AC,AD]=0
$\Rightarrow \left|\begin{array}{ccc}-4& -6& -2\\ -1& 4& 3\\ -8& -1& 3\end{array}\right|=0$