Position vector of \(A = 4\hat{i}+5\hat{j}+\hat{k}\) and Position vector of \(B = -\hat{j}-\hat{k}\)
Position vector of \(C = 3\hat{i}+9\hat{j}+4\hat{k}\) and Position vector of \(D=4(-\hat{i}+\hat{j}+\hat{k})\)
\(\Rightarrow \vec{AB},\vec{AC}\) and \(\vec{AD}\) are coplanar.
\(\Rightarrow A, B, C, D\) are coplanar.