Question

If →a and →b are unit vectors , then what is the angle between →a and →b for →a−√2→b to be a unit vector ?

Answer 1

|a-root2 b|2=1

|a|2+2|b|2-2root2 a.b=1

1+2-2root2|a||b|cos o=1

2-2root2cos o=0

2=2root2 cos o

cos o=2/2root2

cos o=1/root2

o=45