SOLUTION

The tetragonal result from stretching a cubic lattice along with one of its lattice vectors, so that the cube becomes a rectangular prism with a square base (a by a) and height (c, which is different from a).

The tetragonal crystal will have a square base and top, but a taller height. All the three axes should be at the right angle, i.e. α = γ =  β = 90° and two basis vectors must be of equal length a = b ≠ c

a = b ≠ c, α = β = ϒ = 90° axis system is being satisfied by tetragonal crystal system.