All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.
Using Ratio Theorem in MF15,
(a) Since is a unit vector,
It is the length of projection of
This question did not pose much of a problem. Most students were able to identify that comfortably. (iib) however, was not well answered as most students overlooked that is the unit vector here thus the projection should be that of b onto a, instead a onto b. Lastly, students should always check their cross product using scalar product like I always advice in class.