(i) State the algebraic condition that two non–zero vectors a and b must satisfy to be perpendicular and prove the statement.
(ii) State the algebraic condition that two non–zero vectors a and b must satisfy to be parallel (or anti-parallel) and prove the statement.
(iii) Write one explicit pair of non-zero vectors in R3 that are perpendicular and another explicit pair that are parallel, verifying each condition by direct computation.