If a and b are unit vectors and `theta` is the angle between them then `a-b` will be a unit vector if

If a and b are unit vectors and alpha is the angle between them then a - b will be a unit vector if alpha =

If a and b are unit vectors and alpha is the angle between them , then a+b is unit vector when cos alpha =

Let vecaandvecb be two unit vectors and theta is the angle between them Then veca+vecb is a unit vector if