What is the length of the longest pole which can be kept in a room 12 m long, 4 m broad and 3 m high?  Choose the most appropriate option.
A) 7  B) 9  C) 11  D) 13  E) None
Explanation:   d2 = 122 + 42 + 32 = 13   13)
<result>D</result>
What is the length of the longest pole which can be kept in a room 12 m long, 4 m broad and 3 m high?