Question

If a¯,b¯ are non collinear unit vectors, |a¯+b¯|=2 , then (2a¯+5b¯).(3a¯+b¯) =

Answer 1

|a+b| <= |a|+|b|
|a+b| = |a|+|b| only if a and b are collinear

so, bogus problem. they can't be unit vectors whose sum has magnitude 2 unless they are collinear.

Answer 2

1/2