The length of longest rod that can be placed in a room

The length of longest rod that can be placed in a room 20 m long, 16 m broad and 12 m high, is ?

Length of the rod = √(20)² + (16)² + (12)² m
= √800 m
= 20√2 m
= (20 x 1.41) m
= 28.2 m