JEE Main 201912 Apr, Evening shiftMathematicsMediumVector Algebra184× since 2002Let α\alphaα ∈\in∈ R and the three vectors a→=αi^+j^+3k^\overrightarrow a = \alpha \widehat i + \widehat j + 3\widehat ka=αi+j+3k, b→=2i^+j^−αk^\overrightarrow b = 2\widehat i + \widehat j - \alpha \widehat kb=2i+j−αk and c→=αi^−2j^+3k^\overrightarrow c = \alpha \widehat i - 2\widehat j + 3\widehat kc=αi−2j+3k. Then the set S = {α\alphaα : a→\overrightarrow aa , b→\overrightarrow bb and c→\overrightarrow cc are coplanar} :AOption A. contains exactly two numbers only one of which is positiveBOption B. is singletonCOption C. contains exactly two positive numbersDOption D. is emptyCheckSkip · show solution
