c can assume any value there is no restriction for it. Your dot product appears to be correct to me.
Thank you for all your help in my previous posts! Really appreciate them (:
I have this very simple question but maybe I had erred somewhere, I know how to do it but somehow, I don't get an answer.
The coordinates of the points P,Q,R,S are (4,1,-1), (3,3,5), (1,0,2c) and (1,1,2) respectively.
FInd the value of c so that the vectors OR and PR are orthogonal.
I know this means that the dot product of OR and PR should be 0. For PR, I got (-3,-1, 2c+1) and for OR, (1,0,2c). So I dotted them and ended up with an unsolvable quadratic equation, 4c^2+2c-3=0
Is C supposed to be in surd form using the quadratic formula? Or is there something wrong with my dot product?