Câu hỏi 10

\({{{I_1}} \over {{I_2}}} = {\left( {{{{r_2}} \over {{r_1}}}} \right)^2} \Leftrightarrow {1 \over 2} = {\left( {{{{r_2}} \over {{r_1}}}} \right)^2} \Rightarrow {{{r_2}} \over {{r_1}}} = {1 \over {\sqrt 2 }} \Leftrightarrow {r_2} = {1 \over {\sqrt 2 }}d\)

Mà d – r₂ = 50m nên: \(d - {1 \over {\sqrt 2 }}.d = 50 \Rightarrow d = {{50} \over {1 - {1 \over {\sqrt 2 }}}} = 171m\)