Angle between [tex]\vec{A}[/tex] and [tex]\vec{B}[/tex] is 150° .
Now read the question .
The resultant of both vectors is perpendicular to [tex]\vec{B}[/tex]
Look at the attachment
Angle between resultant and vector A be [tex]\theta[/tex]
Let's use maths
[tex]\\ \sf\longmapsto \theta+90°=150°[/tex]
[tex]\\ \sf\longmapsto \theta=150-90[/tex]
[tex]\\ \sf\longmapsto \theta=60°[/tex]
Done
