Question

If a,b and c are three mutually perpendicular vectors, then the projection of the
vectors
l a/|a| + m b/|b| + n (axb) /|axb| along the angle bisector of the vectors a and b is
a. l+m/√2
b. √(l²+m²+n²)
c. √(l²+m²) /√(l²+m²+b²)
d. None of these