unit vector

If the incident ray on a surface is along the unit vector vec v ,the reflected ray is along the unit vector vec w and the normal is along the unit vector vec a outwards,express vec w in terms of vec a and vec v

Consider the following statements : 1. The cross product of two unit vectors is always a unit vector. 2. The dot product of two unit vectors is always unity. 3. The magnitude of sum of two unit vectors is always greater than the magnitude of their difference. Which of the above is not correct?

Given that i-j,i-2j are two vectors.Find a unit vector coplanar with these vectors and, perpendicular to the first vector i-j. Find also the unit vector which is perpendicular to the plane of the two given vectors.