16. The focal chord to $y ^ { 2 } = 16 x$ is tangent to $( x - 6 ) ^ { 2 } + y ^ { 2 } = 2$, then the possible values of the slope of this chord, are : (a) $\{ - 1,1 \}$ (b) $\{ - 2,2 \}$ (c) $\{ - 2,1 / 2 \}$ (d) $\{ 2,1 / 2 \}$
The volume of the parallelopiped formed by vectors $\hat { i } + a \hat { j } + \hat { k } , \hat { j } + a \hat { k }$ and $a \hat { i } + \hat { k } , a > 0$ is minimum when the value of $a$ is
16. The focal chord to $y ^ { 2 } = 16 x$ is tangent to $( x - 6 ) ^ { 2 } + y ^ { 2 } = 2$, then the possible values of the slope of this chord, are :\\
(a) $\{ - 1,1 \}$\\
(b) $\{ - 2,2 \}$\\
(c) $\{ - 2,1 / 2 \}$\\
(d) $\{ 2,1 / 2 \}$\\