Question

what will be the length of the longest pole that can be kept in a room 12m into 9 into 8 m

Answer 1

Given length l = 12 m
 breadth b = 9 m
and height h = 8 m 

Longest rod that can be placed in a room is nothing but its diagonal.

 Length of diagonal of a cuboid = √(l^2 + b^2 + h^2) 

Length of longest rod = √(12^2 + 9^2 + 8^2) m 
= √(144 + 81 + 64) m
= √289 m
 = 17 m

 Thus the length of the longest rod is 17 m.

Answer 2

length will be the lenth of the dioganal of teb room=
$\sqrt{ {12}^{2} + {9}^{2} + {8 }^{2} } = 17m$