Question
If the vectors $(\vec{a} = (c \log_{2} x) \hat{k})$ make an obtuse angle for any $(x \notin (0, \infty))$, then $(c)$ belongs to
If the vectors $(\vec{a} = (c \log_{2} x) \hat{k})$ make an obtuse angle for any $(x \notin (0, \infty))$, then $(c)$ belongs to