JEE PYQ: Vector Algebra Question 38
Question 38 - 2019 (12 Apr Shift 2)
Let $\alpha \in \mathbb{R}$ and the three vectors $\vec{a} = \alpha \hat{i} + \hat{j} + 3\hat{k}$, $\vec{b} = 2\hat{i} + \hat{j} - \alpha \hat{k}$ and $\vec{c} = \alpha \hat{i} - 2\hat{j} + 3\hat{k}$. Then the set $S = {\alpha : \vec{a}, \vec{b} \text{ and } \vec{c} \text{ are coplanar}}$
(1) is singleton
(2) is empty
(3) contains exactly two positive numbers
(4) contains exactly two numbers only one of which is positive
BETA
