Răspuns:
[tex]\boldsymbol {\red{D. \sqrt{2}}}[/tex]
Explicație pas cu pas:
[tex]BD = AB \sqrt{2}[/tex]
[tex]BO = \dfrac{BD}{2} = \dfrac{AB \sqrt{2}}{2}[/tex]
[tex]tg (D'O,(ABC)) = \dfrac{DD'}{DO} = \dfrac{AB}{\dfrac{AB \sqrt{2}}{2}} = \dfrac{2}{\sqrt{2}} = \dfrac{2\sqrt{2}}{2} \\ [/tex]
[tex]\bf tg (D'O,(ABC)) = \sqrt{2}[/tex]