Maximum length of rod which can be fitted in cubical box in Diagonal of cubical box. ∴ Let the diagonal of cubical box is x To find value x, first we have to calculate diagonal length of any face of box. In ∆ABD a=√12+12 ‌‌‌‌‌‌‌‌‌‌‌‌‌‌a=√2m In ∆ABC a2+12=x2 ∴ x=√(2)2+(1)2 ‌‌‌x=√3m