Alright all im on this vector question and im having problems with this question. Part (i) i have no idea what to start with / how i possibly prove the question. This is the question, help will be deeply appriciated. Thanks, David. Also note that || a || = (a_1 + a_2 + ... + 1_n)^1/2 . || a - b || = || a || || b || - 2 (a \cdot b). I have done part (i) :) Its the rest im struggling with.