Question

The distance of the point $\left(\alpha ,\beta ,\gamma \right)$ from y-axis is
$\left(\mathrm{a}\right)\mathrm{\beta }$
$\left(\mathrm{b}\right)\left|\mathrm{\beta }\right|$
$\left(\mathrm{c}\right)\left|\mathrm{\beta }\right|+\left|\mathrm{\gamma }\right|$
$\left(\mathrm{d}\right)\sqrt{{\mathrm{\alpha }}^2+{\mathrm{\gamma }}^2}$

Answer 1

For any point (α, β, γ)
Let (0, β, 0) be a point on y-axis
∴ distance between (α, β, γ) and (0, β, 0) is $\sqrt{{\left(\alpha -0\right)}^2+{\left(\beta -\beta \right)}^2+{\left(\gamma -0\right)}^2}$

i.e $\sqrt{{\alpha }^2+0^2+{\gamma }^2}$
i.e $\sqrt{{\alpha }^2+{\gamma }^2}$

Hence, the correct answer is option D.