Question

find the length of longest stick that can be fitted in a cubical vessel of edge 20 cm long

Answer 1

based on the diagonal of a square now figure it out by yourself.....

Answer 2

the longest length in a cube is of its body diagonal
so,
the length of longest stick that can be fitted in a cubical vessel = length of body diagonal
= √3 a
here a is length of side of cube
so, length of stick = 20√3
= 20 x 1.73 (√3 = 1.73)
= 34.6cm