Suppose that v and w are unit vectors If the angle between v and i is a and the angle between w and i is use the idea of the da following equation cos cos acos sin asin Write the i and j components of v in terms of a Since it is a unit vector the v factor has been omitted v cos a i sin aj Write the i and j components of w in terms of Since it is a unit vector the w factor has been omitted w cos Bi sin j Use these expressions to compute the dot product of v and w in terms of a and B V W