let the unit vector be of the form ai+bj
as it is a unit vector a2+b2=1..............(1)
as it is making an angle of 45 with i+j
so a+b=1......................(2)
from 1 and 2 we get ab=0;
also it is making an angle of 60 with 3i-4j
3a-4b=2.5.........(3)
As there is no equation satisfying 1,2,3 simultaneously there is no such vector
Hence D is the correct answer
Thanks and Regards
Shaik Aasif
askIITians Faculty
