Question

A parallelpiped is formed by planes drawn through the points $(2,3,5)$ and $(5,9,7)$ parallel to the coordinate planes. The length of a diagonal of the parallelopiped is

• A. $7$
• B. $9$
• C. $11$
• D. $\sqrt{155}$

Answer 1

The correct option is A $7$

The lengths of the edges are given by

$a=5-2=3,b=9-3=6,c=7-5=2$

$\therefore$ length of the diagonal $=\sqrt{3^2+6^2+2^2}=\sqrt{49}=7$