panjang diagonal ruang pada balok yang berukuran 5 cm * 4 cm * 2 akar 10 cm adalah

db = diagonal bidang
dr = diagonal ruang
[tex] db \: = \sqrt{ {5}^{2} + {4}^{2} } \\ db \: = \sqrt{25 + 16} \\ db = \sqrt{41} \: cm[/tex]
[tex]dr \: = \sqrt{ { \sqrt{41} }^{2} + {(2 \sqrt{10} )}^{2} } \\ dr \: = \sqrt{41 + 40} \\ dr = \sqrt{81} \\ dr = 9 \: cm[/tex]