Rationalize the Denominator $\mathrm { D } = \sqrt { \mathrm { L } ^ { 2 } + \mathrm { W } ^ { 2 } + \mathrm { H } ^ { 2 } }$

Multiple Choice

Rationalize the denominator. Assume that all variables represent nonnegative numbers and that the denominator is not
zero.
-The length of the diagonal of a box is given by $\mathrm { D } = \sqrt { \mathrm { L } ^ { 2 } + \mathrm { W } ^ { 2 } + \mathrm { H } ^ { 2 } }$ where $\mathrm { L } , \mathrm { W }$ , and $\mathrm { H }$ are the length, width, and height of the box. Find the length of the diagonal, D, of a box that is $2 \mathrm { ft }$ long, $6 \mathrm { ft }$ high, and $4 \mathrm { ft }$ wide. Give the exact value.

A) $48 \mathrm { ft }$
B) $2 \sqrt { 14 } \mathrm { ft }$
C) $12 \mathrm { ft }$
D) $4 \sqrt { 3 } \mathrm { ft }$