Hi there, i'm a bit stuck on this question: " Given 3 non-coplanar vectors a, b and c convince yourself that the position vector r of any point in space may be represented by r = λa + μb + γc for some real numbers λ, μ and γ. Show that r.(bxc) = λa.(bxc) , r.(axb) = γa.(bxc) , r.(cxa) = μa.(bxc) . " I understand how they get the first one - the cross product of b and c is perpendicular to both of them, so won't contain any b or c components. Hence when you do the dot product you'll be multiplying the b and c bits of r by zero so they disappear. However I don't get the other two...? Please help!