For (ii) let the "centre" of the regular hexagon be M ( M is also the common mid-points of AD, BE & CF). All the triangles MAB, MBC, MCD, MDE, MEF & MFA are equilateral. The figure, MABC is made up of triangles MAB & MBC is a rhombus so their diagonals AC & MB are perpendicular to each other. That means z2-z5 is perpendicular to z3-z1.
The diagonals of a kite also intersect at 90 degrees; so should work.
MABC here is both a kite(a kite does not normally have all 4 sides equal; one pair of sides is usually shorter than the other pair) and a rhombus.